sr=input().split()
n=int(sr[0])
m=int(sr[1])
x=int(sr[2])
y=int(sr[3])
a=[[1 for i in range(m+1)] for j in range(n+1)]
s=[[1 for i in range(m+1)] for j in range(n+1)]
a[x][y]=0
s[0][0]=1
if(x+2<=n and y+1<=m):
    a[x+2][y+1]=0
if(x+1<=n and y+2<=m):
    a[x+1][y+2]=0
if(x-1>=0 and y+2<=m):
    a[x-1][y+2]=0
if(x-2>=0 and y+1<=m):
    a[x-2][y+1]=0
if(x-2>=0 and y-1>=0):
    a[x-2][y-1]=0
if(x-1>=0 and y-2>=0):
    a[x-1][y-2]=0
if(x+1<=n and y-2>=0):
    a[x+1][y-2]=0
if(x+2<=n and y-1>=0):
    a[x+2][y-1]=0
for i in range(n+1):
    for j in range(m+1):
        if(a[i][j]==0):
            s[i][j]=0
        elif(i>0 and j>0):
            s[i][j]=s[i-1][j]+s[i][j-1]
        elif(i>0):
            s[i][0]=s[i-1][0]
        elif(j>0):
            s[0][j]=s[0][j-1]
print(s[n][m])
/**************************************************************
	Problem: 1224
	User: admin
	Language: Python
	Result: Accepted
	Time:93 ms
	Memory:34480 kb
****************************************************************/