//p1002 

#include<bits/stdc++.h>

using namespace std;

bool m[30][30];

int x,y,a,b;



long long z[30][30];

long long ans;





int main(){

cin>>x>>y>>a>>b;

m[x][y]=1;

m[x-1][y+2]=1;

m[x+1][y+2]=1;
	m[x+2][y+1]=1;

m[x+2][y-1]=1;

m[x+1][y-2]=1;

m[x-1][y-2]=1;

m[x-2][y-1]=1;

m[x-2][y+1]=1;

for (int i=0;i<a;i++){
		for (int j=0;j<b;j++){

if(i!=1||j!=1&&!m[i][j])z[i][j]=z[i-1][j]+z[i]
[j-1],ans++;



}

}

cout<<ans-23;

return 0;

}

有大佬能帮我看看哪里错了吗？？样例总是输出8.谢谢谢谢