var input = require('fs').readFileSync('/dev/stdin', 'utf8');
var Arr=(input.trim()).split("\n");
var mn=(Arr.shift()).split(" ").map(Number);
var S=[];
for(var i=0;i<mn[0];i++){
   var arr=(Arr.shift()).split(" ").map(Number);
   var sum=arr.reduce(function(a,b){return a+b;});
   S.push(sum);
}
console.log(Math.max.apply(null,S));