N = int(input())
S = list(input())
two = [1] * (N + 1)
mod = 10 ** 9 + 7
for i in range(N):
    two[i + 1] = two[i] * 2 % mod

pre = [0] * 3
for i in range(N):
    dp = [0] * 3
    if S[i] == "A":
        dp[0] = pre[0]
        dp[1] = (pre[2] + two[i]) % mod
        dp[2] = (pre[1] + two[i]) % mod
    elif S[i] == "B":
        dp[1] = pre[1]
        dp[2] = (pre[0] + two[i]) % mod
        dp[0] = (pre[2] + two[i]) % mod
    else:
        dp[2] = pre[2]
        dp[1] = (pre[0] + two[i]) % mod
        dp[0] = (pre[1] + two[i]) % mod
    dp, pre = pre, dp
    
print(pre[0])