#include <bits/stdc++.h>
using namespace std;
using ll=long long;
using ld=double;
#define FOR(i,a,b) for(ll i=a;i<(ll)b;++i)
#define F(n) FOR(i,0,n)
#define FF(n) FOR(j,0,n)
#define aa first
#define bb second
#define PB push_back
#define EQ(a,b) (fabs(a-b)<=(fabs(a+b)*EPS))
#define MOD ((ll)(1e9+7))
#define INF (1ll << 40)

#define MX (500000)
void preKMP(string p, int *f){
	*f=-1;
	for(int i(1),k;p[i];++i){
		k=f[i-1];
		while(~k&&p[k]!=p[i-1])k=f[k];
		f[i]=k+1;
	}
}

int KMP(string p, string t) {
	static int f[MX];
	preKMP(p,f);
  ll x = 0;
  ll k = 0;
  for (int i(0),m(p.size());t[i];) {
    if (k == -1)
      ++ i, k=0;
    else if(t[i]==p[k]){
      //cout << "h" << i << ' ' << k << endl;
      ++ i;
      ++ k;
      //if (++k==m) 
    } else k=f[k];
    //cout << k << ' ' << i << ' '<<  endl;
    if (!t[i]) return k;
  }
	return k;
}

int main() {
  ios::sync_with_stdio(0);cin.tie(0);
  ll N;
  string str;
	cin >> N;
	cin >> str;
	string b = str;
  reverse(b.begin(), b.end());
  //cout << str << endl;
  //cout << b << endl;
  cout << N - KMP(b, str) << endl;
  return 0;
}