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


def is_palindrom(s):
    for i in (0, len(s) // 2):
        if s[i] != s[-(i + 1)]:
            return False
    return True


for i in range(0, n):
    if is_palindrom(c[i:]):
        print(i)
        exit(1)
print(n - 1)