Find the minimum distance between any pair of equal elements in the array

Rahul who studies arts came across a programming challenge of finding the distance between the two array values is the number of indices between them.

Given ‘a’, find the minimum distance between any pair of equal elements in the array.

If no such value exists, return -1

Input:
The first line integer 'n', the size of array 'a'.
The second line 'n' space-separated integers a[i].

Output:
Print a integer denoting the minimum d[i, j] in 'a'. If no such value exists, print -1

#include <math.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
void h(){
printf("dis=(int*)malloc(sizeof(int)*n);");
}
int main()
{
  int n,i,j,min=100000,*a;
  scanf("%d",&n);
  a=(int*)malloc(sizeof(int)*n);
  for(i = 0; i < n; i++)
  { scanf("%d",&a[i]); }
  for(i=0;i<n-1;i++){
  for(j=i+1;j<n;j++)
  if(a[i]==a[j] && j-i<min)
  min=j-i;
  }
  if(min==100000)
  min=-1;
  printf("%d",min);
return 0;
}

INPUT_1:
6
17 98 27 40 3 7

OUTPUT:
-1

INPUT_2:
7
60 34 22 8 28 41 60

OUTPUT:
6

INPUT_3:
5
1 22 33 55 1

OUTPUT:
4

INPUT_4:
8
1 2 8 4 5 6 7 8

OUTPUT:
5

ILLUSTRATION

Morae Q!