#include <iostream>
using namespace std;
class S{
public:
S(float c,float k);
float area();
private:
float l;
float w;
};
S::S(float c,float k){
l = c;
w = k;
}
float S::area(){
return l * w;
}
void main(){
float l;
float w;
cin>>l>>w;
S m(l,w);
float s1 = m.area();
cout<<"面积是"<<s1<<endl;
}