static int sockMerchant(int n, int[] ar) {
        int p, j;
        int aux;
        for (p = 1; p < ar.length; p++){
          aux = ar[p];
          j = p - 1;

          while ((j >= 0) && (aux < ar[j])){
             ar[j + 1] = ar[j];
             j--;
          }
          ar[j + 1] = aux;
        }

        int r = 0;
        int key;
        int t = 0;
        int iguales =0;
        int pares = 0;
        int contpares = 0;
        while (r<n){
            key = ar[t];
            if (key == ar[r]){
                iguales++;
                r++;
                  if(r==n){
                if(iguales > 1){
                pares = iguales / 2;
                contpares = contpares + pares;
              }
            }
            }else{
                t = r;

  if(iguales > 1){
                pares = iguales / 2;
                contpares = contpares + pares;
                iguales = 0;
                pares = 0;
            }else{
                iguales = 0;
            }
            }
        }
        return contpares;
    }