public class Main {

public static class Solution {

int reversePairs(int[] arr, int m) {

int pairs = 0;

for (int i = m - 1, j = arr.length - 1; j >= m; j--) {

for ( ; i >= 0 && arr[i] > arr[j]; i--);

pairs += m - 1 - i;

}

return pairs;

}

}

public static void main(String[] args) {

Solution s = new Solution();

int[] arr = {

1, 4, 8, 9, 2, 3, 6, 7

};

int n = s.reversePairs(arr, 4);

System.out.println(n);

}

}