#include<bits/stdc++.h>

using namespace std;

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    int t;
    cin >> t;
    while(t--)
    {
        int n;
        cin >> n;
        map<int, vector<int>> mp;
        for(int i = 0; i < n; i++)
        {
            int a;
            cin >> a;
            mp[a].push_back(i);
        }
        int ans = n;
        bool f = 1;
        for(auto i : mp)
        {
            auto v = i.second;
            for(int j = 0; j < v.size() - 1; j++)
            {
                f = 0;
                ans = min(ans, v[j + 1] - v[j] + 1);
            }
        }
        if(f)
            cout << -1;
        else
            cout << ans;
        cout << "\n";
    }
}