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#include <iostream>
#include <string>
#include <algorithm>
#include <vector>

using namespace std;

typedef pair<int, vector<bool> > clause;

int s2n(string &s, int p) {
	int r = 0;
	while (p < s.size() && '0' <= s[p] && s[p] <= '9') {
		r = r * 10 + (s[p] - '0');
		p++;
	}
	return r;
}

int mod = (int)10e9 + 7;
vector<int> pow2;

vector<clause> t;

int func(int s, int e, vector<int> &v) {
	if (!v.size()) return pow2[e - s + 1];
	if (s > e) return 0;

	vector<int> v0;
	vector<int> v1;

	int f = 0;

	for (int i = 0; i < v.size(); i++) {
		f = min(f, t[v[i]].first);
		if (t[v[i]].first > s) {
			v0.push_back(v[i]);
			v1.push_back(v[i]);
		} else if (t[v[i]].first + t[v[i]].second.size() <= s) {
			return 0;
		} else {
			int k = s - t[v[i]].first;
			if (t[v[i]].second[k]) {
				v0.push_back(v[i]);
			} else {
				v1.push_back(v[i]);
			}
		}
	}

	if (f > s) {
		v0.clear();
		v1.clear();
		return ((long long)pow2[f - s] * func(f, e, v)) % mod;
	} else {
		return (func(s+1, e, v0) + func(s+1, e, v1)) % mod;
	}
}

int main() {
	ios_base::sync_with_stdio(0);

	int n; string inp;

	getline(cin, inp);
	n = s2n(inp, 0);
	getline(cin, inp);
	pow2.resize(n+1);


	int i = 0;
	vector<pair<int, bool> > cr;
	while (i < inp.size()) {
		if (inp[i] == '(') {
			cr.clear();
		} else if (inp[i] == 'x') {
			cr.push_back(pair<int, bool>(s2n(inp, i+1), inp[i-1] != '~'));
		} else if (inp[i] == ')') {
			clause c;
			sort(cr.begin(), cr.end());
			c.first = cr[0].first;

			for (int j = 0; j < cr.size(); j++) {
				c.second.push_back(cr[j].second);
			}

			t.push_back(c);
		}
		i++;
	}

	pow2[0] = 1;
	for (int i = 1; i <= n; i++) pow2[i] = (pow2[i-1] << 1) % mod;

	vector<int> v;
	for (int i = 0; i < t.size(); i++) v.push_back(i);

	cout << func(1, n, v) << endl;

	return 0;
}