rt，玄关

链接

#include<bits/stdc++.h>
using namespace std;
unsigned long long arr[1000010];
unsigned long long ch;
int main(){
    unsigned long long n;
    cin >> n;
    ch = 1;
    for(int i =1;i<=n;i++){
        cin >> arr[i];
        ch *= arr[i];
    }
    cout << ch;
    return 0;
}