Problem:
Score : 300 points

Problem Statement

Given is a sequence of integers A_1, A_2, ..., A_N.
If its elements are pairwise distinct, print YES; otherwise, print NO.

Constraints

2 ≤ N ≤ 200000

1 ≤ A_i ≤ 10^9

All values in input are integers.

Input

Input is given from Standard Input in the following format:

N
A_1 ... A_N

Output

If the elements of the sequence are pairwise distinct, print YES; otherwise, print NO.

Sample Input 1

5
2 6 1 4 5

Sample Output 1

YES

The elements are pairwise distinct.

Sample Input 2

6
4 1 3 1 6 2

Sample Output 2

NO

The second and fourth elements are identical.

Sample Input 3

2
10000000 10000000

Sample Output 3

NO

Solution in Go (1.6) (judge verdict: Wrong Answer)

package main

import (
  "bufio"
  "fmt"
  "os"
  "strconv"
)

var sc = bufio.NewScanner(os.Stdin)


func next() int {
  sc.Scan()
  i, _ := strconv.Atoi(sc.Text())
  return i
}

func main() {
  sc.Split(bufio.ScanWords)
  n := next()
  arr := make([]int, n)
  isYes := true
  
  for i := 0; i < n; i++ {
    arr[i] = next()
    for j := 0; j < i; j++ {
      if arr[i] == arr[j] {
        isYes = false
      }
    }
  }
  
  if isYes {
    fmt.Println("Yes")
  } else {
    fmt.Println("No")
  }
}