import sys
sys.setrecursionlimit(500000)
l=int(input())
b=input()
def is_palindrom(s):
    #print(s)
    if len(s)<2:
        return True
    if s[0]!=s[-1]:
        return False
    return is_palindrom(s[1:-1])

c=0
for i in range(l-1):
    if b[i]==b[-1]:
        if is_palindrom(b[i:]):
            print(i)
            sys.exit(0)
            
print(l - 1)