TRƯỚC 9 H VỚI AJJJJJJJJJJJJJJJJJJJJJJJJJJJ

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

*Bài 1 :

#include <bits/stdc++.h>
using namespace std;
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);cout.tie(NULL);
    long long a, b, c; cin >> a >> b >> c;
    cout << a*(b+c) + b*(a+c) ;
    return 0;
}

*Bài 2 :

#include <bits/stdc++.h>
using namespace std;
string prime(int n){
    if (n < 2) return "NO";
    for (int i = 2; i < n; i++) if (n % i == 0) return "NO";
    return "YES";
}
int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);cout.tie(NULL);
    string s; cin >> s;
    int ss = 0;
    for(char i:s) ss += i - '0';
    cout << prime(ss);
    return 0;
}