import os import sys visp = [[ 0 for i in range(40)] for j in range(40)] step = [[ 0 for i in range(40)]for j in range(40)] zuobiao = input() h = zuobiao.replace(' ', '') tx, ty , mx, my = int(h[0]), int(h[1]), int(h[2]), int(h[3]) tx += 2 ty += 2 mx += 2 my += 2 hx = [0, -2, -1, 1, 2, 2, 1, -1, -2 ] hy = [ 0, 1, 2, 2, 1, -1, -2, -2, -1 ] for i in range(len(hx)):visp[mx + hx[i]][my + hy[i]] = 1 step[2][1] = 1 for i in range(2, tx+1): for j in range(2, ty+1): if (visp[i][j]):continue step[i][j] = step[i-1][j] + step[i][j-1] print(step[tx][ty])