lattice paths with x/y variables for clarity

import java.io.*;

/*input: int m, int n->  integers of a lattice where m = height and n = width of lattice,
  output: number or ways/paths to get from 0,0 to bottom right
  example: input: 2,3
        output :10
  (2 x 3 lattice of squares)
   *            0  __1 _2 __3
   *            1 |__ |__|__|
   *            2 |__ |__|__|
   *
   * ***work this going from top down--from input to 0,0. when
   *   0 is reached that is a base case

   * n+ m = number of steps total
   (n+m)!/ (n!m!) is the total paths possible
   ex: (2,3) --> 5!/3!2!--> 5*4*3*2*1/3*2*1*2*1
   --> 5*2= 10 possible paths
  */
class MyCode {

  public static void main(String[] args){
    int x = 10;
    int y = 10;
    System.out.println(countPaths(x,y));

  }

  public static int countPaths(int x, int y){
    if(x == 0 && y == 0){
      return 1; //only 1 way to start at start
    }
    if(x == -1 || y == -1){
      return 0; //not possible to be out of bounds
    }

    int countLeft = countPaths(x, y-1);// width/y-axis chgs
    int countUp = countPaths(x-1, y); // height/x-axis chgs
    return countUp + countLeft;
  }
}