var
r1, r2:real;
begin
write('R1 = '); readln(r1);
write('R2 = '); readln(r2);
writeln('Площадь кольца равна ', pi * (r1 * r1 - r2 *r2));
end.
var
r1, r2:real;
begin
write('R1 = '); readln(r1);
write('R2 = '); readln(r2);
writeln('Площадь кольца равна ', pi * (r1 * r1 - r2 *r2));
end.