#include <iostream>
 #include <type_traits>

 template<typename T>
 T gcd(T a, T b){
   static_assert(std::is_integral<T>::value, "T should be an integral type!");
   if( b == 0 ){ return a; }
   else{
     return gcd(b, a % b);
   }
 }

 int main(){

   std::cout << std::endl;

   std::cout << gcd(3.5,4.0)<< std::endl;
   std::cout << gcd("100","10") << std::endl;

   std::cout << std::endl;

 }