uses crt;
var a, b : integer;
function tong(x,y : integer): integer;
var i,t : integer;
begin clrscr;
t:=0;
for i :=x to y do if i mod 2 = 0 then t:=t+i;
tong:=t; end;
begin clrscr;
write('Nhap hai so a,b :'); readln(a,b);
write('Tong cac so chan tu ',a,' den ',b,' la :', tong(a,b));
readln
end.