2.1基本算法之枚举 7827.质数的和与积

#include <bits/stdc++.h>
using namespace std;
bool prime(int n){
        for(int i=2;i<=sqrt(n);++i){
          if(n%i==0){
          return 0;
          }
        }
        return 1;
}
int main(){
        int s;
        int sum = 0;
        scanf("%d",&s);
        for(int i=s/2;i>=2;i--){
          int j = s-i;
          if(prime(i)==1 && prime(j)==1){
           sum = i*j;
           break;
          }
        }
        cout<<sum;
        return 0;
}