#include <bits/stdc++.h>

using namespace std;

#define ll long long

ll llA[105][105] = {0};
ll llB[105][105] = {0};

void work(ll llX, ll llY)
{
    llB[llX][llY] = 1;
    llB[llX - 1][llY - 2] = 1;
    llB[llX - 2][llY - 1] = 1;
    llB[llX - 2][llY + 1] = 1;
    llB[llX - 1][llY + 2] = 1;
    llB[llX + 1][llY - 2] = 1;
    llB[llX + 2][llY - 1] = 1;
    llB[llX + 2][llY + 1] = 1;
    llB[llX + 1][llY + 2] = 1;
}

int main()
{
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    
    ll llA2 = 0;
    ll llB2 = 0;
    ll llN = 0;
    ll llM = 0;
    
    cin >> llN >> llM >> llA2 >> llB2;
    
    llN++;
    llM++;
    llA2++;
    llB2++;
    
    work(llA2, llB2);
    
    llA[1][1] = 1;
    
    for (ll i = 1; i <= llN; i++)
    {
        for (ll j = 1; j <= llM; j++)
        {
        	if ((i == 1) && (j == 1))
        	{
        	    continue;
        	}
        	
        	if (llB[i][j] == 0)
        	{
        	    llA[i][j] = llA[i - 1][j] + llA[i][j - 1];
        	}
        }
    }
    
    cout << llA[llN][llM] << endl;
    
    return 0;
}

大佬求助