//#include <iostream>
//#include <cstdio>
//#include "string"
#include <bits/stdc++.h>
#include "stack"

using namespace std;

int main()
{
    int n;
    string str;
    cin>>n>>str;
    int maxlen=0;
    for(int len=1;len<=n;len++){
        int flag=0;
        for(int i=0;i<=n-len;i++){
            string sub=str.substr(i,len);
            string shengyu=str.substr(i+len,n-len-i);
            //cout<<sub<<"\n"<<shengyu<<endl;
            if((int)shengyu.find(sub)!=-1){
                flag=1;
                break;
            }
        }
        if(flag){
            if(len>maxlen){
                maxlen=len;
                //cout<<maxlen<<endl;
            }
        }
    }
    cout<<maxlen+1;
    return 0;
}