program bai1;
var i,n,s:longint;
begin
write('N= ');readln(n);
s:=0;
for i:=1 to n do
s:=s+i;
writeln('Tong la ',s);
readl
end.
var n,i,s:longint;
begin
write('nhap so n=');readln(n);
s:=0;
for i:=1 to n do s:=s+i;
writeln(' tong n so nguyen la:',s);
readln;
end.
program bai1;
var i,n,s:longint;
begin
write('N= ');readln(n);
s:=0;
for i:=1 to n do
s:=s+i;
writeln('Tong la ',s);
readl
end.