Program kolco;
const p=3.14;
var radius_kolca, radius_otverstia, S_kolca:integer;
begin
Writeln("Vvedite radius kolca");
Readln(radius_kolca);
Writeln("Vvedite radius otverstia");
Readln(radius_otverstia);
if radius_otverstia>radius_kolca then
writeln("radius_otverstia ne mozhet bit bolshe radius_kolca")
else S_kolca:=p*(sqr(radius_kolca)-sqr(radius_otverstia));
writeln(S_kolca);
end.