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

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