public int solve(int[] arr, int key){
int n = arr.length;
int start = 0, end = (n-1), ans = -1;
while(start <= end){
int mid = start + (end - start)/2;
if(arr[mid] <= key){
start = mid + 1;
ans = mid;
}
else{
end = mid -1;
}
}
return ans + 1;
}