#include <cassert>
#include <cmath>
#include <iostream>
using namespace std;

template<int mod>
class modint {
    int val = 0;
    constexpr static int normalize(long long x) {
        if (0 <= x and x < mod) return static_cast<int>(x);
        else { x %= mod; return static_cast<int>(x >= 0 ? x : x + mod); }
    }
public:
    static const int modulus = mod;
    modint() {}
    constexpr modint(long long n) : val(normalize(n)) {}
    constexpr int value() const { return val; }
    constexpr modint operator-() const { return modint(mod - val); }
    constexpr modint inverse() const {
        long long x = mod, y = val, p = 1, q = 0, r = 0, s = 1;
        while (y != 0) {
            long long u = x / y;
            long long x0 = y; y = x - y * u; x = x0;
            long long r0 = p - r * u, s0 = q - s * u;
            p = r; r = r0; q = s; s = s0;
        }
        return modint(q);
    }
    constexpr const modint pow(long long e) const {
        if (e < 0) return pow(-e).inverse();
        long long ans = 1, p = val;
        while (e > 0) {
            if (e % 2 != 0) ans = (ans * p) % mod;
            p = (p * p) % mod;
            e >>= 1;
        }
        return modint(ans);
    }
    constexpr modint &operator+=(const modint r) {
        val += r.value();
        if (val >= mod) val -= mod;
        return *this;
    }
    constexpr modint &operator-=(const modint r) {
        val -= r.value();
        if (val < 0) val += mod;
        return *this;
    }
    constexpr modint &operator*=(const modint r) {
        val = (long long)val * r.value() % mod;
        return *this;
    }
    constexpr modint &operator/=(const modint r) {
        if (r.value() == 2) {
            val = (val % 2 ? val + mod : val) / 2;
        } else {
            val = (long long)val * r.inverse().value() % mod;
        }
        return *this;
    }

    friend constexpr modint operator+(const modint l, const modint r) {
        const int newval = l.value() + r.value();
        return newval >= mod ? newval - mod : newval;
    }
    friend constexpr modint operator-(const modint l, const modint r) { return l + (- r); }
    friend constexpr modint operator*(const modint l, const modint r) { return (long long)l.value() * r.value(); }
    friend constexpr modint operator/(const modint l, const modint r) { return l * r.inverse(); }
    friend constexpr bool operator==(const modint l, const modint r) { return l.value() == r.value(); }
    friend constexpr bool operator!=(const modint l, const modint r) { return l.value() != r.value(); }
};

constexpr int M = 1000000007;
using mint = modint<M>;

mint solve(const string &s, int i, char target) {
    assert(i < s.size());
    while (i >= 0 && s[i] == target) i--;
    if (i < 0) return 0;
    if (i == 0) return 1;
    const char x = s[i], y = 'A' ^ 'B' ^ 'C' ^ x ^ target;
    return solve(s, i - 1, y) + mint(2).pow(i);
}

int main() {
    int n; cin >> n;
    string s; cin >> s;
    cout << solve(s, n - 1, 'A').value() << endl;
}