n,m,x,y = map(int,input().split())
hf = [[-1,2],[1,2],[2,1],[2,-1],[1,-2],[-1,-2],[-2,-1],[-2,1],[0,0]] #合法的相对坐标
dp = [[1] *(n+1) for i in range(m+1)] #计算马兰过河卒的坐标
for i in range(9):
    hf[i] = [hf[i][0]+x,hf[i][1]+y]
#初始化合法的坐标
#初始化dp数组
for i in range(1,n+1):
    for j in range(1,m+1):
        if [i,j] in hf: #不需要考虑越界的情况
            dp[i][j] = 0
        else:
            dp[i][j] = dp[i-1][j]+dp[i][j-1]
print(dp[-1][-1])