import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.nio.charset.StandardCharsets;
import java.util.InputMismatchException;
import java.util.PriorityQueue;

public class c {

	static class Solver {

		@SuppressWarnings("unchecked")
		PriorityQueue<Integer> occ[] = new PriorityQueue[200010];
		
		public Solver() {
			for(int i = 0; i < occ.length; i++)
				occ[i] = new PriorityQueue<>();			
		}
		
		int N, oo = 987654321, min;
		
		void solve(FastScanner s, PrintWriter out) {
			N = s.nextInt(); min = oo;
			for(int i = 0; i < N; i++)
				occ[s.nextInt()].add(i);
			for(int i = 1; i <= N; i++) {
				if(occ[i].isEmpty()) continue;
				int f = occ[i].poll(), g;
				while(!occ[i].isEmpty()) {
					min = min(min, (g = occ[i].poll()) - f);
					f = g;
				}
			}
			out.println(min == oo ? -1 : min + 1);
		}
		
		int min(int a, int b) { return a < b ? a : b; }

	}

	public static void main(String[] args) {
		FastScanner s = new FastScanner(System.in);
		PrintWriter out = new PrintWriter(System.out);
		Solver solver = new Solver();
		for(int t = 1, T = s.nextInt(); t <= T; t++)
			solver.solve(s, out);
		out.close();
		s.close();
	}

	static class FastScanner {
		private InputStream stream;
		private byte[] buf = new byte[1 << 22];
		private int curChar;
		private int numChars;

		public FastScanner(InputStream stream) {
			this.stream = stream;
		}

		public FastScanner(File f) throws FileNotFoundException {
			this(new FileInputStream(f));
		}

		public FastScanner(String s) {
			this.stream = new ByteArrayInputStream(s.getBytes(StandardCharsets.UTF_8));
		}

		void close() {
			try {
				stream.close();
			} catch (IOException e) {
				e.printStackTrace();
			}
		}

		int read() {
			if (numChars == -1)
				throw new InputMismatchException();
			if (curChar >= numChars) {
				curChar = 0;
				try {
					numChars = stream.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (numChars <= 0)
					return -1;
			}
			return buf[curChar++];
		}

		boolean isSpaceChar(int c) {
			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
		}

		boolean isEndline(int c) {
			return c == '\n' || c == '\r' || c == -1;
		}

		public int nextInt() {
			return Integer.parseInt(next());
		}

		public long nextLong() {
			return Long.parseLong(next());
		}

		public double nextDouble() {
			return Double.parseDouble(next());
		}

		public String next() {
			int c = read();
			while (isSpaceChar(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isSpaceChar(c));
			return res.toString();
		}

		public String nextLine() {
			int c = read();
			while (isEndline(c))
				c = read();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(c);
				c = read();
			} while (!isEndline(c));
			return res.toString();
		}

		public int[] nextIntArray(int N) {
			int[] ret = new int[N];
			for (int i = 0; i < N; i++)
				ret[i] = this.nextInt();
			return ret;
		}

		public int[][] next2DIntArray(int N, int M) {
			int[][] ret = new int[N][];
			for (int i = 0; i < N; i++)
				ret[i] = this.nextIntArray(M);
			return ret;
		}

		public long[] nextLongArray(int N) {
			long[] ret = new long[N];
			for (int i = 0; i < N; i++)
				ret[i] = this.nextLong();
			return ret;
		}

		public long[][] next2DLongArray(int N, int M) {
			long[][] ret = new long[N][];
			for (int i = 0; i < N; i++)
				ret[i] = nextLongArray(M);
			return ret;
		}

		public double[] nextDoubleArray(int N) {
			double[] ret = new double[N];
			for (int i = 0; i < N; i++)
				ret[i] = this.nextDouble();
			return ret;
		}

		public double[][] next2DDoubleArray(int N, int M) {
			double[][] ret = new double[N][];
			for (int i = 0; i < N; i++)
				ret[i] = this.nextDoubleArray(M);
			return ret;
		}

	}

}
