#include<bits/stdc++.h>
namespace {
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-function"
#include<atcoder/all>
#pragma GCC diagnostic pop
using namespace std;
using namespace atcoder;
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; i--)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
template<class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } else return false; }
template<class T> bool chmin(T& a, const T& b) { if (b < a) { a = b; return true; } else return false; }
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;
using mint = modint1000000007;

} int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n;
  string s;
  cin >> n >> s;
  char tgt = 'A';
  mint ans;
  mint p2 = mint(2).pow(n - 1);
  const mint inv2 = mint(2).inv();
  rrep(i, n) {
    if (s[i] != tgt) {
      tgt = 'A' ^ 'B' ^ 'C' ^ tgt ^ s[i];
      ans += p2;
    }
    p2 *= inv2;
  }
  cout << ans.val() << '\n';
}