#include <bits/stdc++.h>
#define ll long long
#define REP(i, n) for(int i=0;i<n;i++)
#define MOD ((ll) 4503599627370551)

using namespace std;

int n;
char arr[1000000];
ll pows[1000000];


ll h1 = 1;
ll h2 = 1;

int main(){
    cin >> n;
    REP(i, n) {
        cin >> arr[i];
        arr[i] -= 'a'-1;
    }

    // REP(i, n) cout << (int)arr[i] << " ";
    // cout << endl;

    if (n == 1) {
        cout << 0 << endl;
        return 0;
    }

    pows[0] = 1;
    for(int i=1;i<300000;i++){
        pows[i] = pows[i-1] * 26;
        pows[i] %= MOD;
    }

    int best = 1;
    if (arr[n-1] == arr[n-2]) best = 2;


    h1 = arr[n-1];
    h2 = arr[n-2];
    for(int i=1; i<=n/2; i++){
        ll p1 = arr[n-i-1] * pows[i];
        p1 %= MOD;
        h1 += p1;
        h1 %= MOD;

        h2 *= 26;
        h2 %= MOD;
        h2 += arr[n-2*i-1];
        h2 %= MOD;

        // cout << h1 << " " << h2 << endl; 

        if (h1 == h2) {
            best = max(2*i+1, best);
        }

        if (n-2*i-2 < 0) break;

        h2 -= p1;
        h2 += MOD;
        h2 %= MOD;
        h2 *= 26;
        h2 %= MOD;
        h2 += arr[n-2*i-2];
        h2 %= MOD;

        if (h1 == h2) {
           best = max(2*i+2, best);
        }
    }
    // cout << best << endl;
    cout << n-best << endl;
}