Julka

#include<bits/stdc++.h>
using namespace std;
int main(){
  string s;
  int n;
  cin >> n >> s;
  int wazne, P[n + 7], k;
  P[0] = 0;
  for(int i = 1;i < n;i++){
    k = P[i - 1];
    while(k > 0 && s[i] != s[k])
      k = P[k-1];
    if(s[i] == s[k])
      k++;
    P[i] = k;
  }
  wazne = P[n-1];
  for(int i = 0;i < n - 1 - P[n-1];i++){
    P[i] = P[i + P[n - 1]];
  }
  k = 0;
  for(int i = 1;i < n - 2 * P[n-1];i++){
    while(k > 0 && s[i] != s[k])
      k = P[k-1];
    if(s[i]==s[k])
      k=k+1;
    P[i]=k;
  }
  cout<< P[n - 2 * P[n - 1] - 1] + wazne;
}