#include<bits/stdc++.h>
using namespace std;
int lb;
char b[1000001];
int kmp[1000001];
int main(){
	scanf("%d%s",&lb,b+1);
	int j=0;
	for(int i=2;i<=lb;i++){
		while(j>0&&b[i]!=b[j+1])j=kmp[j-1];
		if(b[i]==b[j+1])j++;
		kmp[i]=j;
	}
	cout<<lb-kmp[lb];
	return 0;
}