#include<bits/stdc++.h>
using namespace std;
int dp[1000000];
int len,j;
string s;
void read(int &h){
    char o;
    int x=0,y=1;
    o=getchar_unlocked();
    while(!(o<='9'&&o>='0')){
        if(o=='-'){
            y=-1;
        }
        o=getchar_unlocked();
    }
    while(o<='9'&&o>='0'){
        x*=10;
        x+=o-'0';
        o=getchar_unlocked();
    }
    h=x*y;
    return ;
}
int main() {
    read(len);
    cin>>s;
    s=" "+s;
    for (int i=1;i<len;i++) {
        while (j&&s[i+1]!=s[j+1]) {
            j=dp[j];
        }
        if (s[i+1]==s[j+1]) {
            j++;
        }
        dp[i+1]=j;
    }
    cout<<len-dp[len]<<endl;
    return 0;
}