#include <stdio.h>
#include <string>
#include <vector>
#include <iostream>
#include <fstream>
#include <algorithm>
#include <set>
#include <map>
#include <list>
#include <deque>
#include <memory>
#include <utility>
#include <queue>
#include <math.h>
#include <ctime>
#include <random>
#include <functional>

using namespace std;

int main() {
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	int q;
	cin >> q;
	for (int i = 0; i < q; i++) {
		int n;
		cin >> n;
		vector<int> v(n);
		for (int i = 0; i < n; i++) {
			cin >> v[i];
		}


		map<int, int> mapa;
		int l = 0, r = 1;
		mapa[v[0]]++;
		int ans = 1e9;
		while (r < n) {
			mapa[v[r]]++;
			if (mapa[v[r]] >= 2) {
				while (v[l] != v[r]) {
					mapa[v[l]]--;
					l++;
				}
				ans = min(ans, r - l + 1);
				l++;
				mapa[v[r]]--;
			}
			r++;
		}
		if (ans == 1e9)
			cout << "-1\n";
		else
			cout << ans << '\n';
	}

	return 0;
}