C++!!!!!!!!!!!!!!!!!!!!!!!!!!

#include <bits/stdc++.h>

using namespace std;
bool scp(long long n)
{
    long long  k = sqrt(n);
    if (k * k == n) return true;
    else return false;
}
int main()
{
    long long n;
    cin>>n;
    if(scp(n)) cout<<"YES";
    else cout<<"NO";
}

\begin{array}{c} \color{#db1616}{\texttt{#Khoadang09}} \end{array}

- AC trên LQDOJ, không chắc AC web khác

#include <bits/stdc++.h>
#define ll long long
using namespace std;
void check(ll n){
    if (n==pow(round(pow(n,0.5)),2)) cout << "YES";
    else cout << "NO";
}
int main(){
    ll n; cin >> n;
    check(n);
}