var lines = require("fs").readFileSync("/dev/stdin", "utf8").split("\n");
var buf = lines[0].split(' ');
var N = parseInt(buf[0]);
var W = parseInt(buf[1]);

var weightList = [];
for(var i=1; i<N+1; i++){
    var line = lines[i].split(' ');

    var weight = parseInt(line[1]);
    
    if(weight <= W){
        weightList.push(parseInt(line[0]));
    }
}

if(weightList.length === 0){
    console.log("-1");
} else {
    console.log(Math.max.apply(null, weightList));
}