using System;

using System.Collections.Generic;

​

public class Program

{

    public static void Main()

    {

        List<int> arr = new List<int>(){7, 1, 3, 4, 1, 7};

        Console.WriteLine(minimumDistances(arr));

    }

​

    public static int minimumDistances(List<int> a)

{

    int minValue = int.MaxValue; // Initialize the minimum distance as a large value

    Dictionary<int, int> lastIndex = new Dictionary<int, int>(); // Store the last index of each element

    for (int i = 0; i < a.Count; i++)

    {

        int element = a[i];

        if (lastIndex.ContainsKey(element))

        {

            int distance = i - lastIndex[element];

            minValue = Math.Min(minValue, distance);

        }

        lastIndex[element] = i;

    }

    if (minValue == int.MaxValue)

    {

        return -1; // No equal elements found

    }

    return minValue;

}

​

}