program ct;
uses crt;
var a:integer; b:integer; h:integer; S:integer;
begin
clrscr;
writeln('moi bạn nhap vào do dai hai day hinh thang : '); readln(a,b);
writel(' Moi ban nhap vao chieu cao hinh thang : '); readln(h);
S:=h*((a+b)/2);
writeln('Dien tich hinh thang la: ');
write(S);
readln;
end.