Problem tich;
uses crt;
var a,b,c,d: real;
begin
    write('nhap a = '); readln(a);
    write('nhap b = '); readln(b);
    write('nhap c = '); readln(c);
    write('nhap d = '); readln(d);
    writeln(a*b*c*d,0,2);
    readln;
end.