#include<iostream>
using namespace std;
int prim(int n){
if(n<=1) return 0;
if(n<=3) return 1;
if(n%2==0||n%3==0) return 0;
for(int i=5;i*i<=n;i+=6) if(n%i==0||n%(i+2)==0) return 0;
return 1;
}
int main(){
int a, b;
cin>>a>>b;
if(prim(a)==1&&prim(b)==1) cout<<a+b;
else cout<<a*b;
}
