var
R,S:real;
begin
readln (R);
S:=3.14*R*R;
writeln (S);
end.
Program chislo;
uses crt;
var
a:integer;
begin
writeln('Введите число : ');
readln(a);
if((a Div 100)>(a Mod 10)) then
writeln('Да')
else
if((a Div 100)<(a Mod 10)) then
writeln('Нет')
end.
var x,y:real;
begin
writeln('Введите значение x: ');
readln(x);
if x<0 then
begin
y:=x/2;
writeln('y = ',y);
end
else
begin
if x>=0 then
y:=sqrt(3+x);
writeln('y = ',y);
end;
end.