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++ (GCC 9.2.1) (judge verdict: Accepted)

//Distinct or Not

#include<bits/stdc++.h>
using namespace std;
using ll = long long;
#define int long long
#define rep(i,x,y) for(ll i=x;i<y;i++)
#define nvarep(n,a) ll n;cin>>n;vector<ll>a(n);rep(i,0,n)cin>>a[i]
#define vecrep(n,a,type) vector<type>a(n);rep(i,0,n)cin>>a[i]
#define lcm(a,b) (a/__gcd(a, b)*b)
#define range(a) (a).begin(),(a).end() 
#define pb push_back
#define mp make_pair
#define nnn "\n"
#define spa " "
using P = pair<ll,ll>;
using graph = vector<vector<ll>>;
const int inf = 2147483647;//2*10^9
const ll INF = 9223372036854775807;//9*10^18

signed main (){
    nvarep(n,a);
    set<int>m;
    rep(i,0,n){
        if(!m.insert(a[i]).second){
            cout<<"NO"<<nnn;
            return 0;
        }
    }
    cout<<"YES"<<nnn;
    return 0;
}