第1题：请写出程序运行后变量sum的值（6分）
program xx07_1;
const maxn=1000000;
var n,k,sum:longint;
f:array[1..maxn] of 0..1;
begin
readln(n);
for k:=1 to n do f[k]:=1;
for k:=1 to n div 2 do f[k*2]:=0;
for k:=1 to n div 3 do f[k*3]:=0;
sum:=0;
for k:=1 to n do sum:=sum+f[k];
writeln('sum=',sum);
end.
输入：1000
输出：sum=333