program gf;
uses crt;
var i: integer;
tong: integer;
begin
clrscr;
tong:=0;
for i:= 1 to 50 do
if i mod 2 = 1 then tong:= tong + i;
write('Tong cac so le trong khoang 1 den 50 la:, tong);
readln
end.
uses crt;
var i,n:integer;
a:longint;
begin
writeln('nhap n');readln(n);
a:=0;
for i:=1 to 49 do
if i mod 2<>0 then
a:=a+i;
writeln(a);
readln
end.