"use strict";

// よそからもらってきたコード
function existsSameValue(a){
  let s = new Set(a);
  return s.size != a.length;
}

function Main(input) {
  let N = input.trim().split("\n")[0];
  let Nums = input.trim().split("\n")[1].split(" ").map(x=> x*1);
  let isDouble = existsSameValue(Nums);
  let ans = "YES";
  if(isDouble){
  	ans = "NO"
  }
  
  console.log(`${ans}`);
}

Main(require("fs").readFileSync("/dev/stdin", "utf8"));

