//Bai 7
 
#include<bits/stdc++.h>
using namespace std;
#define el "\n"
#define ll long long
#define ull unsigned long long
#define se second
#define fi first
#define be begin()
#define en end()
#define Faster cin.tie(0); cout.tie(0); ios_base::sync_with_stdio(0);
 
void Run(int n, ll a[])
{
    ll ans = 1;
    for(int i = 0; i < n; i++)
    {
        cin >> a[i];
        if(i % 2 == 0) ans *= a[i];
    }
    cout << ans;
}
int main()
{
    Faster;
    int n; cin >> n;
    ll a[n];
    Run(n, a);
    return 0;
}
 
 

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