#include<iostream>
using namespace std;
int main(){
float a,b,c,d;
cin>>a>>b>>c>>d;
cout<<a*b*c*d;
return 0;
}
var
a,b,c,d: real;
begin
read(a);
read(b);
read(c);
read(d);
write(a*b*c*d);
end;
citeste a,b,c,d
scrie a*b*c*d
a = float(input())
b = float(input())
c = float(input())
d = float(input())
sum = a*b*c*d
print(sum)