n = int(input())
s = input()
mod = 10**9 + 7

t = 1
DP = [0 for _ in range(3)]
NDP = [0 for _ in range(3)]
for i in range(n):
    idx = ord(s[i]) - ord('A')
    for j in range(3):
        if j == idx:
            NDP[j] = DP[j]
        else:
            NDP[j] = (DP[3 - j - idx] + t) % mod
    DP = NDP[:]
    t *= 2
    t %= mod
print(DP[0])