var a,b,c:longint;
s,p:real;
begin
write('nhap a,b,c: '); readln(a,b,c);
if a+b>c then write('Khong phai la tam giac') else
if a+c>b then write('Khong phai la tam giac') else
if b+c>a then write('Khong phai la tam giac') else
writeln('La tam giac');
p:=(a+b+c)/2;
s:=sqrt(p*(p-a)*(p-b)*(p-c));
write('Dien tich tam giac la: ',s:0:4);
readln;
end.