'use strict'


function Main(input) {
  input = input.trim().split('\n')
  const N = parseInt(input[0])

  const A = input[1].split(' ').map(s => parseInt(s))

  let dp = {}
  for(let i = 0; i < N; ++i) {
    if(dp[A[i]]) {
      console.log('No')
      return
    } else {
      dp[A[i]] = 0
    }
    dp[A[i]] += 1
  }

  console.log('Yes')
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));