#pragma region Macros
#include <bits/stdc++.h>
#if defined(LOCAL) || defined(ONLINE_JUDGE) || defined(_DEBUG)
#include <atcoder/all>
#endif
using namespace std;
#define REP(i, n) for(int i=0, i##_len=(n); i<i##_len; ++i)
#define REPR(i, n) for(int i=(n); i>=0; --i)
#define FOR(i, n, m) for(int i=(m), i##_len=(n); i<i##_len; ++i)
#define EACH(i, v) for(const auto& i : v)
#define ALL(x) (x).begin(),(x).end()
#define ALLR(x) (x).rbegin(),(x).rend()
template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; }
template<class T>using vec = vector<T>;
template<class T, class U>using umap = unordered_map<T, U>;
template<class T>using uset = unordered_set<T>;
using ll = long long;
using ld = long double;
using P = pair<ll, ll>;
using T = tuple<ll, ll, ll>;
using vl = vec<ll>;
#define fi first
#define se second
#define el endl
constexpr ll INF = numeric_limits<ll>::max()/2-1;
#pragma endregion

#pragma region IOMacros
template<class T>
istream &operator>>(istream &stream, vec<T>& o){REP(i, o.size())stream >> o[i];return stream;}
template<class T>
ostream &operator<<(ostream &stream, vec<T>& objs){REP(i, objs.size())stream << objs[i] << " ";stream << el;return stream;}

#define I(T, ...) ;T __VA_ARGS__;__i(__VA_ARGS__);
void __i() {}
template<class T, class... Ts> void __i(T&& o, Ts&&... args){cin >> o;__i(forward<Ts>(args)...);}

void O() {cout << el;}
template<class T, class... Ts> void O(T&& o, Ts&&... args){cerr << o << " ";O(forward<Ts>(args)...);}
#pragma endregion

void Main();

int main(){
    std::cin.tie(nullptr);
    std::cout << std::fixed << std::setprecision(15);
    Main();
    return 0;
}

ll H, W;
ll pos(ll h, ll w){
    if(h < 0 || h >= H || w < 0 || w >= W) return H*W;
    return h*W + w;
}

bool ho(string state, ll h, ll w){
    return state[pos(h, w)] == '.';
}

uset<string> seen;
ll fn(string state, ll A){
    if(seen.find(state) != seen.end()){
        return 0;
    }
    seen.insert(state);
    if(A == 0){
        //O(state);
        return 1;
    }
    ll ret = 0;
    REP(i, H){
        REP(j, W){
            if(!ho(state, i, j))continue;
            string M;
            if(ho(state, i+1, j)){
                M = state;
                M[pos(i, j)] = 'v';
                M[pos(i+1, j)] = '^';
                ret += fn(M, A-1);
            }
            if(ho(state, i, j+1)){
                M = state;
                M[pos(i, j)] = '>';
                M[pos(i, j+1)] = '<';
                ret += fn(M, A-1);
            }
        }
    }
    return ret;
}
void Main(){
    cin >> H >> W;
    I(ll, A, B);
    string S(H*W+1, '.');
    S[H*W] = '#';
    cout << fn(S, A) << el;
}

#include <iostream>
#include <sstream>
#include <iomanip>
#include <vector>
#include <deque>
#include <list>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <bitset>
#include <string>
#include <numeric>
#include <algorithm>
#include <functional>
#include <iterator>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <cstdlib>
#include <cctype>
#include <complex>
#include <ctime>
#define ll long long
#define inf 0x3f3f3f3f
#define N 20
//ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
using namespace std;
int H,W,A,B,ans;
bool mp[N][N];

void dfs(int a,int b)
{
    if(a==0&&b==0)
    {
        ans++;
        return ;
    }
    bool flag=true;
    for(int i=1;i<=H&&flag;i++)
        for(int j=1;j<=W&&flag;j++)
        {
            if(!mp[i][j])
            {
                if(i<H&&!mp[i+1][j])
                {
                    mp[i][j]=true;
                    mp[i+1][j]=true;
                    dfs(a-1,b);
                    mp[i][j]=false;
                    mp[i+1][j]=false;
                }
                if(j<W&&!mp[i][j+1])
                {
                    mp[i][j]=true;
                    mp[i][j+1]=true;
                    dfs(a-1,b);
                    mp[i][j]=false;
                    mp[i][j+1]=false;
                }
                mp[i][j]=true;
                dfs(a,b-1);
                mp[i][j]=false;
                flag=false;
            }
        }
}

signed main(){
    scanf("%d%d%d%d",&H,&W,&A,&B);
    dfs(A,B);
    printf("%d\n",ans);
	return 0;
}
