先感谢前帖的两位dalao为我解答了18行的错误

有没有人来教一下我其他错误，例如23行，谢谢dalao

#include<bits/stdc++.h>
using namespace std;
#define maxn 1000010
int n,N,x,pri[10000];
typedef long long LL;
bool a[maxn];
int Eratosthenes_sieve(int n,int pri[]){
	for (int i=2;i*i<=n;i++)
		if(a[i]==0)
			for(int j= i<<1;j<=n;j+=i)
				a[j] =1;
	int cnt=0;
	for(int i = 2;i<=n;i++)
		if(!a[i])pri[cnt++] = i;
	return cnt;
}
int main(){
	int cnt = Eratosthenes_sieve(50000,pri);
	LL L,R;
	scanf("%lld %lld",&L,&R);
	memset(a,0,sizeof(a));
	for(int i = 0;i<cnt;i++)
		for(LL j = max(211,(L-1)/pri[i]+1)*pri[i];j<=R;j +=pri[i])
			a[j-L] = 1;
	int ans=0;
	for(LL i = L;i<=R;i++)
		if(a[i-L] == 0)ans++;
	printf("%d",ans);
	return 0;
}