Intersection of Two Linked Lists

public class Solution {
    public ListNode getIntersectionNode(ListNode headA, ListNode headB) {
        if(headA == null || headB == null) return null;
        int m = 0;
        ListNode startA = headA;
        ListNode startB = headB;
        while(headA.next != null)
        {
            headA = headA.next;
            m++;
        }
        int n = 0;
        while(headB.next != null)
        {
            headB = headB.next;
            n++;
        }
        if(headA != headB)  return null;
        if(m > n)
        {
            int gap = m - n;
            for(int i = 0; i < gap; i++)
            {
                startA = startA.next;
            }
        }
        else
        {
            int gap = n - m;
            for(int i = 0; i < gap; i++)
            {
                startB = startB.next;
            }
        }
        while(startA != startB)
        {
            startA = startA.next;
            startB = startB.next;
        }
        return startA;
    }
}