func_code_string: #include <bits/stdc++.h>   using namespace std;   const long long mod = 1e9 + 7;   void solve() {     int n;     cin >> n;     string s;     cin >> s;     long long ans = 0;     long long ca = 0, cab = 0, cabc = 0, slen = 1;     for (char c : s) {       if (c ==  a )         ca = (slen + ca) % mod;       else if (c ==  b )         cab = (ca + cab) % mod;       else if (c ==  c )         cabc = (cabc + cab) % mod;       else {         cabc = (3 * cabc + cab) % mod;         cab = (ca + 3 * cab) % mod;         ca = (slen + 3 * ca) % mod;         slen = (3 * slen) % mod;       }     }     cout << cabc <<   n ;   }   int main() {     ios::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     ;     int t = 1;     while (t--) {       solve();     }     return 0;   }   