var n,i,s:integer;
begin
writeln('n='); readln(n); s:=0;
for i:=1 to n do if i mod 2 <> 0 then s:=s+i;
writeln('Tong cac so le nho hon hoac bang n la:',s); readln
end.
var n,i,s:integer;
begin
writeln('n='); readln(n); s:=0;
for i:=1 to n do if i mod 2 <> 0 then s:=s+i;
writeln('Tong cac so le nho hon hoac bang n la:',s); readln
end.