#include <iostream> using namespace std; int main (){ int n; cin >> n; bool a=0; if(n1){ a=1; } for(int i=2;i*i<=n;i++){ if(n%i0){ a=1; } } if(a==0){ cout << "YE5"; }else{ cout<<"N0"; } return 0; } //注意题目的YES和NO