is there a link for the problem?

This problem is the OV problem with $$$\log$$$ bits, it cannot be solved better than $$$\mathcal O(nv)$$$.

I am not sure this solution is right, so do not blame me if I wrong(XD.
Due to I do not know link to test, I can only give you this $$$O(v^2)$$$ solution of DP

//Retired?
#include <bits/stdc++.h>
#define int long long
using namespace std;
const int N = 1e6 + 10, mod = 1e9 + 7;
signed main(){
    std::ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);

    int n; cin >> n;

    vector<int> a(n + 1);
    vector<int> dp((1 << 14) | 1, 1e9);
    for(int i = 1; i <= n; i++){
        cin >> a[i];
        dp[a[i]] = 1;
    }

    sort(a.begin() + 1, a.end());
    a.erase(unique(a.begin() + 1, a.end()), a.end());
    n = a.size() - 1;

    for(int i = 1; i <= n; i++){
        for(int j = 0; j <= (1 << 14); j++){
            dp[j & a[i]] = min(dp[j & a[i]], dp[j] + 1); 
        }
    }

    cout << (dp[0] == 1e9 ? -1 : dp[0]) << '\n';

    return 0;
}