n = int(input())
c = input()

j = 1
p_len = 0
for i in range(0, n):
    if c[i] == c[-j]:
        j += 1
    else:
        j = 1
        if c[i] == c[-j]:
            p_len = i
            j += 1
        else:
            p_len = i + 1
    if i + j >= n:
        print(p_len)
        exit(0)
print(p_len)