#include <iostream>
#include <fstream>

using namespace std;

int main()
{
    int i,g,w,mat[2][1001]={0},celMaiMic = 10002;;
    fstream in("energii.in");
    fstream out("energii.out");
    in >> g >> w;
    for(i=0;i<g;i++){
        in >> mat[0][i];
        in >> mat[1][i];
    }

    for(i=0;i<g;i++){
        if(mat[0][i]==w && mat[1][i]<celMaiMic) celMaiMic=mat[1][i];
    }

    if(celMaiMic!=1002)out << celMaiMic;
    else out << "0";

    in.close();
    out.close();
}