public class SmallSum {    public static void mergeSort(int[] arr) {        if (arr == null || arr.length < 2) {            return;        }        mergeSort(arr, 0, arr.length - 1);    }    static int sum=0;    static void mergeSort(int a[],int l,int r) {        if(l==r) {            return;        }        int m = l+((r-l)>>1);        mergeSort(a, l, m);        mergeSort(a, m+1, r);        merge(a,l,m,r);    }        static void merge(int a[],int l,int m,int r) {        int[] help = new int[r-l+1];        int p1=l;        int p2=m+1;        int i=0;        while(p1<=m&&p2<=r) {            sum+=a[p1]