# include<iostream> # include<cstdio> using namespace std; int main(){ /* int a,b,n; cin>>a>>b; n=a*b; cout<<n; */ /* int a,b,c,n; cin>>a>>b>>c; n=a*b*c; cout<<n; */ /* int a,b,c,n; cin>>a>>b>>c; n=(a+b)/c; cout<<n; */ /* for(int i=1;i<=100;i++){ if(i%3==0){ continue; } cout<<i<<endl; } */ /* int y; for(int i=1;i<=100;i++){ if(i%3==0){ y=i%10; if(y==0){ y=y+10; } cout<<y<<" "; } continue; } */ int a,i,T=1; cin>>a; for(i=2;i<a;i++){ if(a%i==0){ T=0; break; } } if(T==0){ cout<<"NO"; }else{ cout<<"YES"; } return 0; }