#include<bits/stdc++.h>
using namespace std;
#define VI vector<int>
#define PII pair<int, int>
#define VPI vector<PII>
#define mp make_pair
#define eb emplace_back
#define pb push_back
#define st first
#define nd second
#define endl '\n'
#define debug(x) cerr << #x << " " << x << endl;
#define ll long long

//#define int ll

const int N = 2e6 + 7;

char tbl[N];

int r[N];

void Manacher(const char* s, int n, int* r) {
	for (int i = 0, m = 0, k = 0, p = 0; i < 2 * n - 1; m = i++ - 1) {
		while (p < k and i / 2 + r[m] != k)
			r[i++] = min(r[m--], (k + 1 - p++) / 2);
		while (k + 1 < n and p > 0 and s[k + 1] == s[p - 1])
			k++, p--;
		r[i] = (k + 1 - p++) / 2;
	}
}

bool is_pal(int p, int k) {
	return r[p + k] >= (k - p + 1) / 2;
}
		

void solve(){
	int n;
	cin >> n;
	for (int i = 0; i < n; i++) {
		cin >> tbl[i];
	}
	Manacher(tbl, n, r);
	for (int i = n; i > 0; i--) {
		if (is_pal(n - i, n - 1)) {
			cout << n - i << "\n";
			return;
		}
	}
	cout << n - 1 << "\n";
	return;
}

int32_t main(){
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	
	int test = 1;
	
	while(test--){
		solve();
	}
	
	return 0;
}