program Ls112kfdkfjfj;
const pi=3.14;
var n,m: real;
function S(r: real): real;
begin
     S:=pi*r*r;
end;
begin
     write('R1='); readln(n); n:=S(n);
     write('R2='); readln(m); m:=S(m);
     writeln('S=',abs(n-m));
end.