//Matija Herceg
#include<iostream>
#include<cmath>
#include<cstring>
#include<cstdio>
#include<cstdlib>
#include<vector>
#include<fstream>
#include<string>
#include<algorithm>
#include<list>

using namespace std;

int main(){
    int n,m,rj=0,a,b;
    cin>>n>>m;
    for (int i=0; i<n; i++){
        cin>>a>>b;
        rj=max(rj,b);
    }
    cout<<rj;
    //system("pause");
    return 0;
}