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#include<bits/stdc++.h>
using namespace std;
# ifdef DEB
# define debug(...) fprintf(stderr, __VA_ARGS__)
# else
# define debug(...)
#endif
#define F first
#define S second
#define MP make_pair
#define PB push_back
#define LL long long
#define LD long double
#define PII pair<int, int>
#define PLL pair<LL, LL>
#define pb pop_back
#define VI vector<int> 
#define VPI vector<PII> 
#define FOR(i,a,b) for(int i = (a); i <= (b); i++)
#define FORD(i,a,b) for(int i = (a); i >= (b); i--)
#define RE(i,n) FOR(i,1,n)
#define REP(i,n) FOR(i,0,(int)(n)-1)
#define ALL(x) (x).begin(), (x).end()
#define siz(V) ((int)V.size())
const int M=1e6+5;
const LL mod=1e9+7;

struct Node
{
  bool end;
  Node* s[2];
  int val;
};

bool B[M];
int n, l, dp[M];
char C[20000000];
Node * T[M], * nothing;

void addtotrie(Node* root, int start, int end)
{
  if(start<end)
  {
    root->end=true;
    return;
  }
  //debug("adding %d %d\n", start, end);
  if(root->s[B[start]]==NULL)
    root->s[B[start]]=new Node();
  addtotrie(root->s[B[start]], start-1, end);
}

void getclause(int ind)
{
  int mini=n, maxi=0;
  while(C[ind]!=')')
  {
    bool boo=1;
    ind++;
    if(C[ind]=='~')
    {
      boo=0;
      ind++;
    }
    ind++;
    int num=atoi(C+ind);
    //debug("%d %d\n", ind, num);
    while(C[ind]!=')' && C[ind]!='v')
      ind++;
    if(C[ind]=='v')
      ind++;
    mini=min(mini, num);
    maxi=max(maxi, num);
    B[num]=boo;
  }
  //debug("clause from %d to %d\n", mini, maxi);
  addtotrie(T[maxi], maxi, mini);
}

void parseinput()
{
  REP(i, l)
    if(C[i]=='(')
      getclause(i);
}

void dfs(Node* root, Node* mir, int ind)
{
  //debug("in: %d %d %d\n", root->val, mir->val, ind);
  if(mir->val==0 || root->end)
    return;
  REP(i, 2)
  {
    //if(i==0)
    //  debug("hmm %d %d %d\n", root->s[i]==NULL, mir->s[i]==NULL, ind);
    if(root->s[i]==NULL)
    {
      if(mir->s[i]==NULL)
        root->val+=dp[ind-1];
      else
      {
        root->s[i]=mir->s[i];
        root->val+=mir->s[i]->val;
      }
    }
    else
    {
      if(mir->s[i]==NULL)
        dfs(root->s[i], nothing, ind-1);
      else
        dfs(root->s[i], mir->s[i], ind-1);
      root->val+=root->s[i]->val;
    }
  }
  if(root->val>=mod)
    root->val-=mod;
  //debug("val= %d\n", root->val);
}

void go(int ind)
{
  REP(i, 2)
  {
    if(T[ind]->s[i]==NULL)
    {
      T[ind]->val+=dp[ind-1];
      if(ind>1)
        T[ind]->s[i]=T[ind-1];
    }
    else
    {
      //debug("going %d -> %d\n", ind, i);
      dfs(T[ind]->s[i], T[ind-1], ind-1);
      T[ind]->val+=T[ind]->s[i]->val;
    }
  }
  if(T[ind]->val>=mod)
    T[ind]->val-=mod;
  dp[ind]=T[ind]->val;
}

int main()
{
  nothing=new Node();
  nothing->val=1;
  scanf("%d\n", &n);
  REP(i, n+1)
    T[i]=new Node();
  dp[0]=1;
  fgets(C, 1e9, stdin);
  l=strlen(C)-1;
  //debug("%s", C);
  parseinput();
  RE(i, n)
    go(i);
  printf("%d\n", dp[n]);
  return 0;
}