#include <atcoder/all>
using namespace std;
using mint = atcoder::modint1000000007;

int main(){
    string s;
    cin >> s >> s;
    mint ans;
    char c = 'B' ^ 'C', p = 0;
    for(int i = s.size(); i >= 0; i--){
        if(s[i] != 'A'){
            p = s[i];
            c ^= p;
            break;
        }
    }
    while(s.size()){
        c ^= 'A' ^ 'B' ^ 'C' ^ p;
        while(s.size() && s.back() == c)s.pop_back();
        if(s.size()){
            ans += mint(2).pow(s.size() - 1);
            p = c;
            c = s.back();
            s.pop_back();
        }
    }
    cout << ans.val() << '\n';
}