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import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.*;

/**
 * Created by konrad on 26.11.16.
 */
public class cnf {

    public static long MOD = 1_000_000_000 + 7;

    public static int extractLiteral(String literal) {
        int start = 1;
        int mul = 1;
        if (literal.startsWith("(")) {
            start = 2;
        }
        if (literal.charAt(start -1) == '~') {
            mul = -1;
            start ++;
        }
        int end = literal.length();
        if (literal.endsWith(")")) {
            end --;
        }
        return mul * Integer.parseInt(literal.substring(start, end));
    }

    public static Clause parseClause(StringTokenizer st) {
        Clause clause = new Clause();
        String current = st.nextToken();
        while (!current.endsWith(")")) {
            if ("v".equals(current) || "^".equals(current)) {
                current = st.nextToken();
                continue;
            }
            clause.addLiteral(extractLiteral(current));
            current = st.nextToken();
        }

        clause.addLiteral(extractLiteral(current));
        return clause;

    }

    public static class Clause {
        Set<Integer> literals = new HashSet<>();
        int max = Integer.MIN_VALUE;
        int min = Integer.MAX_VALUE;

        public void addLiteral(int i) {
            int ai = Math.abs(i);
            max = Math.max(max, ai);
            min = Math.min(min, ai);
            literals.add(i);
        }

        public int size() {
            return literals.size();
        }

        public boolean isSubsetOf(Clause other) {
            return other.min <= min && max <= other.max;
        }

        public boolean containsLiteral(int literal) {
            return literals.contains(literal);
        }

        public boolean makesTrue(int i) {
            return literals.contains(i);
        }

        public String toString() {
            ArrayList<Integer> tmp = new ArrayList<>(literals);
            Collections.sort(tmp);
            return tmp.toString();
        }

    }
    static class Pair<T, P> {
        T fst;
        P snd;

        public Pair(T fst, P snd) {
            this.fst = fst;
            this.snd = snd;
        }
        public String toString() {
            return "(" + fst + "," + snd + ")";
        }
    }

    static public class SatisfactionKeeper {

        HashSet<Integer> satisfiedClauses = new HashSet<>();
        Stack<Pair<Integer, Integer>> history = new Stack<>();

        void markSatisfied(int atLiteral, int clauseId) {
            satisfiedClauses.add(clauseId);
            history.add(new Pair<>(atLiteral, clauseId));
        }

        void dropTillIncluding(int atLiteral) {
            while (history.size() >0 && history.peek().fst >= atLiteral) {
                satisfiedClauses.remove(history.pop().snd);
            }
        }

        boolean isSatisfied(int clauseId) {
            return satisfiedClauses.contains(clauseId);
        }

        public String toString() {
            return history.toString();
        }
    }


    static ArrayList<Clause> clauses = new ArrayList<>();

    static ArrayList<ArrayList<Integer>> literalToClauses = new ArrayList<>();

    static SatisfactionKeeper satisfactionKeeper = new SatisfactionKeeper();

    static int[] starts;
    static int n;
    static int N;

    static long pow2[];

    private static int computeJump(int literalSetToTrue) {
        int literal = Math.abs(literalSetToTrue);
        int maxJump = literal + 1;
        for (Integer ci : literalToClauses.get(literal)) {
            Clause c = clauses.get(ci);
            if (c.makesTrue(literalSetToTrue) && !satisfactionKeeper.isSatisfied(ci)) {
                satisfactionKeeper.markSatisfied(literal, ci);
            }
            if (satisfactionKeeper.isSatisfied(ci)) {
                maxJump = Math.max(c.max + 1, maxJump);
            } else if (c.max == literal) {
//                System.out.println("NEG:" + literalSetToTrue + "  " + c.literals);
                return 0;
            } else {
                maxJump = literal + 1;
                break;
            }
        }
        maxJump = Math.min(starts[literal], maxJump);
//        System.out.println("computed jump for: " + literalSetToTrue + " : " + maxJump);
        return maxJump;
    }

    private static long multShift(int jump, long val) {
//        System.out.println("Using shift: " + (jump - 1));
        return (pow2[jump - 1] * val) % MOD;
    }

    private static long subSolve(int literalSetToTrue, ArrayList<Long> multiplies) {
//        System.out.println("subsolve: " + literalSetToTrue);
        int literal = Math.abs(literalSetToTrue);
        int maxJump = computeJump(literalSetToTrue);
        if (maxJump == 0) return 0;
        long subSolve = solve(maxJump, multiplies);
        long ret = multShift(maxJump - literal, subSolve);
//        System.out.println(subSolve + "  ------  " + subSolve);
        return ret;
    }

    private static long solve(int literal, ArrayList<Long> multiplies) {
//        System.out.println("Solve for: " + literal + " : " + multiplies);
//        System.out.println(satisfactionKeeper);
        if (literal > n) {
            return 1;
        }

        if (multiplies.get(literal) == -1) {

            long positiveCase = subSolve(literal, multiplies);
            satisfactionKeeper.dropTillIncluding(literal);
            long negativeCase = subSolve(-literal, multiplies);
            satisfactionKeeper.dropTillIncluding(literal);
            long multiplier = (positiveCase + negativeCase) % MOD;
            multiplies.set(literal, multiplier);
        }
//        System.out.println(literal + " : " + multiplies);
        return multiplies.get(literal);
    }


    public static void computeStarts() {
        starts = new int[N];
        for (Clause c: clauses) {
            starts[c.min] = 1;
        }
        int lastStart = Integer.MAX_VALUE;
        for (int i=n; i>0;i--) {
            int val = starts[i];
            starts[i] = lastStart;
            if (val == 1) {
                lastStart = i;
            }
        }
//        System.out.println("STARTS" + Arrays.toString(starts));
    }

    public static void main(String[] args) throws IOException {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        String line = br.readLine();
        n = Integer.parseInt(line);
        N = n +1;

        pow2 = new long[N];
        pow2[0] = 1;
        for (int i=1;i<N;i++) {
            pow2[i] = (pow2[i-1] << 1) % MOD;
        }

        line = br.readLine();
        StringTokenizer st = new StringTokenizer(line);

        for (int i=0; i < N; i++) {
            literalToClauses.add(new ArrayList<>());
        }

        while (st.hasMoreTokens()) {
            Clause clause = parseClause(st);
            int m = clauses.size();
            clauses.add(clause);
            for (Integer literal : clause.literals) {
                ArrayList<Integer> literalClauses = literalToClauses.get(Math.abs(literal));
                literalClauses.add(m);
            }
        }

        computeStarts();

        ArrayList<Long> multipliers = new ArrayList<>(N);
        for (int i=0; i< N;i++) {
            multipliers.add(-1L);
        }

        System.out.println(solve(1, multipliers));

//        long baseMultiplier = 1;
//        ArrayList<Integer> currentLiterals = new ArrayList<>();
//        for (int i=1;i<=n;i++) {
//            ArrayList<Integer> iClauses = literalToClauses.get(i);
//            // multiply on non-present literals
//            if (iClauses.isEmpty()) {
//                baseMultiplier = (baseMultiplier << 1) % MOD;
//                continue;
//            }
//            // remove single literals
//            int pos = 0;
//            int neg = 0;
//            for (Integer c : iClauses) {
//                Clause cl = clauses.get(c);
//                if (cl.size() > 1) {
//                    currentLiterals.add(i);
//                    continue;
//                }
//                if (cl.makesTrue(i)) {
//                    pos ++;
//                } else {
//                    neg++;
//                }
//            }
//            if (neg > 0 && pos > 0) {
//                System.out.println(0);
//                System.exit(0);
//            }
//        }
    }
}