rt.下面这段代码把freopen批注掉的时候运行得好好的不批注掉就RE(指本地测试return3221225620),求助为啥

#include"bits/stdc++.h"
using namespace std;
int main()
{
	freopen("pocky.in","r",stdin);
	freopen("pocky.out","w",stdout);
	int l,k,ans;
	scanf("%d%d",&l,&k);
	ans=((l-(l%(2*k)))/2);
	printf("%d",ans);
	return 0;
}