uses crt;
var a, b, c, p, s, cv : real;
begin
clrscr;
write('Nhap ba so a, b, c : '); readln(a, b, c);
if (a > 0) and (b > 0) and (c > 0) then
if (a + b > c) and (a + c > b) and (c + a > b) then
begin
writeln('Ba canh la do dai tam giac');
cv := a + b + c;
p := (a + b + c) / 2;
s := sqrt(p * (p - a) * (p - b) * (p - c));
writeln('Chu vi : ', cv : 2 : 1);
writeln('Dien tich : ', s : 2 : 1);
end
else writeln('Ba so khong la do dai tam giac')
else writeln('Ba so khong la do dai tam giac');
readln
end.