import sys

N = int(input())
S = input()
MOD = 10 ** 9 + 7

sys.setrecursionlimit(10 ** 5)


def rest(s1: str, s2: str):
    st = set("ABC")
    st.remove(s1)
    st.remove(s2)
    return st.pop()


pow_table = [1] * (N + 1)
for i in range(1, N + 1):
    pow_table[i] = pow_table[i - 1] * 2 % MOD


def f(i: int, s: str):
    if S[i] == s:
        if i:
            return f(i - 1, s)
        else:
            return 0
    else:
        if i:
            res = f(i - 1, rest(S[i], s)) + pow_table[i]
            return res % MOD
        else:
            return 1


print(f(N - 1, "A"))