#include<iostream> // cin\cout\endl #include<cstdio> //scanf()\printf() #include<cstring> // strcpy()\strcat()\strcmp()\strlen()\memset() #include<cmath> //sqrt()\pow()\abs()\ceil()\floor()\max()\min() using namespace std; int main(){ int n; cin>>n; while(n%i!=0&&n!=1){ i++; } if(i==n) cout<<"YES"<<endl; else cout<<"NO"endl return 0; }