uses crt;
var a, b, c, s, p : real;
begin
clrscr;
write('Nhap 3 canh tam giac : ');
readln(a, b, c);
if (a < 50) and (b < 50) and (c < 50) then
begin p := (a + b + c) / 2;
s := sqrt(p * (p - a) * (p - b) * (p - c));
write('Dien tich = ', s : 2 : 2);
end; readln
end.