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 C++ (Clang 3.8.0) (judge verdict: Wrong Answer)

#include<iostream> 
#include<string>
#include<cstring>
#include<algorithm>
#include<cstdio>
#include<cmath>
#include<set>
#include<map>
#include<vector>
#include<queue>
#include<sstream>
#include<iomanip>
using namespace std;

#define sf scanf
#define pf printf
#define pfn printf("\n");
#define pfk printf(" ");
#define pf0 printf("0");
#define pf1 printf("1");
#define ll long long
#define sfd(n) scanf("%d",&n);
#define sfdd(n,m) scanf("%d%d",&n,&m);
#define sfld(n) scanf("%lld",&n);
#define sfldd(n,m) scanf("%lld%lld",&n,&m);
#define sflf(n) scanf("%lf",&n);
#define sflff(n,m) scanf("%lf%lf",&n,&m);
#define sfc(n) scanf("%c",n);
#define sfcc(n,m) scanf("%c%c",n,m);
#define sfs(n) scanf("%s",n);
#define sfss(n,m) scanf("%s%s",n,m);
#define pfd(n) printf("%d",n);
#define pfld(n) printf("%lld",n);
#define pflf(n) printf("%lf",n);
#define pfc(n) printf("%c",n);
#define pfs(n) printf("%s",n);

#define csh(a,n) memset(a,n,sizeof(a));

int main(){
	int n;
	cin>>n;
	map<int,int>mp;
	for(int i=0;i<n;i++){
		int a;
		if(mp[a]==1){
			cout<<"NO"<<endl;
			return 0;
		}
		else{
			mp[a]=1;
		}
	}
	cout<<"YES"<<endl;
}