#include<iostream> using namespace std; int main(){ int a,b,i=2; int c = 2; cin>>a>>b; a = 15; b = 18; bool flag = false; while(i<b&&i<a){ if(b % c==0 && a%i ==0){ flag = true; break; } i--; } if(flag){ cout<<i<<endl; } return 0; }