program class1q2b; uses wincrt;
const G = 6.64E-11;
var m1, m2, r, F : real;
begin
  write('What is the mass on which the force is acting? ');
  readln(m1);
  write('What is the force acting? ');
  readln(F);
  write('What is the radius? ');
  readln(r);
  writeln;
  m2 := F/G*(r*r)/m1;
  writeln('The mass is ',m2,' kg.')
end.