#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ii = pair<int, int>;
using i3 = pair<int, ii>;
using li = pair<ll, int>;
using lii = pair<ll, ii>;
using pll = pair<ll, ll>;
using vi = vector<int>;
using vl = vector<ll>;
using vii = vector<ii>;
using vpll = vector<pll>;
using vi3 = vector<i3>;
using vlii = vector<lii>;
const int N = 2e5 + 5;
const ll INF = 1e17 + 7;
const double eps = 1e-9, PI = acos(-1);
int n, m;
vi adj[N];
set<int> st;
void solve(int testCase) {
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) {
    int x;
    scanf("%d", &x);
    adj[x].push_back(i);
    st.insert(x);
  }
  int ans = 1e9;
  for (int i : st) {
    if (adj[i].size() >= 2) {
      for (int j = 1; j < adj[i].size(); j++) {
        ans = min(ans, adj[i][j] - adj[i][j - 1] + 1);
      }
    }
    adj[i].clear();
  }
  st.clear();
  printf("%d\n", ans == 1e9 ? -1 : ans);
}
int main() {
  int t = 1;
  scanf("%d", &t);
  for (int testCase = 1; testCase <= t; testCase++) {
    solve(testCase);
  }
  return 0;
}
