1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
#include <bits/stdc++.h>
#define MP make_pair
#define PB push_back
#define int long long
#define st first
#define nd second
#define rd third
#define FOR(i, a, b) for(int i =(a); i <=(b); ++i)
#define RE(i, n) FOR(i, 1, n)
#define FORD(i, a, b) for(int i = (a); i >= (b); --i)
#define REP(i, n) for(int i = 0;i <(n); ++i)
#define VAR(v, i) __typeof(i) v=(i)
#define FORE(i, c) for(VAR(i, (c).begin()); i != (c).end(); ++i)
#define ALL(x) (x).begin(), (x).end()
#define SZ(x) ((int)(x).size())
using namespace std;
template<typename TH> void _dbg(const char* sdbg, TH h) { cerr<<sdbg<<"="<<h<<"\n"; }
template<typename TH, typename... TA> void _dbg(const char* sdbg, TH h, TA... t) {
  while(*sdbg != ',')cerr<<*sdbg++; cerr<<"="<<h<<","; _dbg(sdbg+1, t...);
}
#ifdef LOCAL
#define debug(...) _dbg(#__VA_ARGS__, __VA_ARGS__)
#define debugv(x) {{cerr <<#x <<" = "; FORE(itt, (x)) cerr <<*itt <<", "; cerr <<"\n"; }}
#else
#define debug(...) (__VA_ARGS__)
#define debugv(x)
#define cerr if(0)cout
#endif
#define next ____next
#define prev ____prev
#define left ____left
#define hash ____hash
typedef long long ll;
typedef long double LD;
typedef pair<int, int> PII;
typedef pair<ll, ll> PLL;
typedef vector<int> VI;
typedef vector<VI> VVI;
typedef vector<ll> VLL;
typedef vector<pair<int, int> > VPII;
typedef vector<pair<ll, ll> > VPLL;

template<class C> void mini(C&a4, C b4){a4=min(a4, b4); }
template<class C> void maxi(C&a4, C b4){a4=max(a4, b4); }
template<class T1, class T2>
ostream& operator<< (ostream &out, pair<T1, T2> pair) { return out << "(" << pair.first << ", " << pair.second << ")";}
template<class A, class B, class C> struct Triple { A first; B second; C third;
  bool operator<(const Triple& t) const { if (st != t.st) return st < t.st; if (nd != t.nd) return nd < t.nd; return rd < t.rd; } };
template<class T> void ResizeVec(T&, vector<int>) {}
template<class T> void ResizeVec(vector<T>& vec, vector<int> sz) {
  vec.resize(sz[0]); sz.erase(sz.begin()); if (sz.empty()) { return; }
  for (T& v : vec) { ResizeVec(v, sz); }
}
typedef Triple<int, int, int> TIII;
template<class A, class B, class C>
ostream& operator<< (ostream &out, Triple<A, B, C> t) { return out << "(" << t.st << ", " << t.nd << ", " << t.rd << ")"; }
template<class T> ostream& operator<<(ostream& out, vector<T> vec) { out<<"("; for (auto& v: vec) out<<v<<", "; return out<<")"; }

const int P = 1e9 + 7;
    
struct Node {
  VI children;
  int val;
  VI which;
};

struct Word {
  int beg;
  VI let;
  int OnPos(int en) {
    assert(en - beg < SZ(let));
    return let[en - beg];
  }
  bool IsEnd(int pos) {
    return pos - beg == SZ(let) - 1;
  }
};
const int N = 1e6 + 5;
Word words[N];
VI which_start[N];
int32_t main() {

  ios_base::sync_with_stdio(0);
  cout << fixed << setprecision(10);
  cerr << fixed << setprecision(10);
  cin.tie(0);
  //double beg_clock = 1.0 * clock() / CLOCKS_PER_SEC;
  
  int n;
  cin>>n;
  string s;
  vector<VPII> all;
  VPII cur;
  int cnt = 0;
  while (cin>>s) {
    bool should_end = false;
    if (s.back() == ')') {
      should_end = true;
      s.pop_back();
    }
    if (s.back() == '^' || s.back() == 'v') {
      continue;
    }
    if (s[0] == '(') {
      s = s.substr(1);
    }
    int forb = 0;
    if (s[0] == '~') {
      forb = 1;
      s = s.substr(1);
    }
    int ind = stoi(s.substr(1));
    cur.PB({ind, forb});
    if (should_end) {
      sort(ALL(cur));
      cnt++;
      words[cnt].beg = cur[0].st;
      for (auto p : cur) {
        words[cnt].let.PB(p.nd);
      }
      which_start[cur[0].st].PB(cnt);
      //all.PB(cur);
      cur.clear();
    }
  }
  //debug(all);
  
  vector<Node> tree{{{}, 1, {}}};
  RE (pos, n) {
    vector<Node> new_tree;
    for (auto x : which_start[pos]) {
      tree[0].which.PB(x);
    }
    new_tree.PB({{}, 0, {}}); // TODO ??
    function<void(int, VI)> Dfs = [&](int v, VI links) {
      VI ends(2);
      VVI which(2);
      for (auto word_ind : tree[v].which) {
        Word& w = words[word_ind];
        REP (add, 2) {
          if (w.OnPos(pos) == add) {
            if (w.IsEnd(pos)) {
              ends[add] = true;
            } else {
              which[add].PB(word_ind);
            }
          }
        }
      }
      REP (add, 2) {
        if (links[add] == -1 || ends[add]) {
          links[add] = -1;
        } else {
          if (which[add].empty()) {
            new_tree[links[add]].val = (new_tree[links[add]].val + tree[v].val) % P;
          } else {
            new_tree[links[add]].children.PB(SZ(new_tree));
            links[add] = SZ(new_tree);
            new_tree.PB({{}, tree[v].val, which[add]});
          }
        } 
      }
      for (auto nei : tree[v].children) {
        Dfs(nei, links);
      }
    };
    Dfs(0, {0, 0});
    swap(tree, new_tree);
  }
  int ans = 0;
  for (auto x : tree) {
    ans = (ans + x.val) % P;
  }
  cout<<ans<<endl;
  return 0;
}