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: Accepted)

package main
import "fmt"
func main(){
    // Your code here!
    var n int
    fmt.Scan(&n)
    t := make([]string, n)
    for i := 0; i < n; i++ {
        fmt.Scan(&t[i])
    }
    
    if true == check_uniq(t){
        fmt.Println("YES")
    }else{
        fmt.Println("NO")
    }
}

func check_uniq(origin []string) bool{
    m := make(map[string]bool)
    uniq := [] string{}
    for _, ele := range origin {
        if !m[ele] {
            m[ele] = true
            uniq = append(uniq, ele)
        }
    }
    if len(origin) == len(m){
        return true
    }
    return false
}