int differentValues(int[] a, int d) {
int max = -1;
for (int i = 0; i < a.length - 1; i++) {
for (int j = i + 1; j< a.length; j++) {
if (Math.abs(a[i] - a[j]) <= d && max < Math.abs(a[i] - a[j])) max = Math.abs(a[i] - a[j]);
}
}
return max;
}