Torry的困惑(基本型)

#include<iostream>
#include<cstring>
using namespace std;
int arr[1300005];
void f(){
	memset(arr,0,sizeof(arr));
	arr[0]=1;
	arr[1]=1;
	int count=0;
	for(int i=2;i<1300005;i++){
		if(!arr[i])
		{
			count++;
			for(int j=i+i;j<1300005;j+=i){
				arr[j]=1;			
			}
		}
	}
	
	//ut<<count<<endl;
}
int main(){
	int n;
	cin>>n;
	f();
	int m=0,i=0,sum=1;
	while(m!=n){
		if(!arr[i]){
			sum=(sum*i)%50000;
			m++;
		}
		i++;
	}
	cout<<sum;
	return 0;
}