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.