G TAP 2017

#include <bits/stdc++.h>
using namespace std;
#define dprint(v) cerr << #v"=" << v << endl //;)
#define forr(i,a,b) for(int i=(a); i<(b); i++)
#define forn(i,n) forr(i,0,n)
#define dforn(i,n) for(int i=n-1; i>=0; i--)
#define forall(it,v) for(auto it=v.begin();it!=v.end();++it)
#define sz(c) ((int)c.size())
#define zero(v) memset(v, 0, sizeof(v))
#define pb push_back
#define fst first
#define snd second
typedef long long ll;
typedef pair<int,int> ii;

const ll MOD = 1e9+7;
int N,M,P1,P2;
ll comb[110][110], dp[110][1010];

int main() {
    //~ freopen("in", "r", stdin);
    ios::sync_with_stdio(0);
    while(cin >> N >> M >> P1 >> P2){
        dp[0][0]=1;
        forr(p,1,1001) dp[0][p]=0;
        forr(x,1,N+1) forn(p,1001) {
            dp[x][p] = 0;
            forr(i,1,min(p,M)+1) {
                dp[x][p] = (dp[x][p]+dp[x-1][p-i])%MOD;
            }
        }
        forn(i, 105){
            comb[i][0]=comb[i][i]=1;
            forr(k, 1, i) comb[i][k]=(comb[i-1][k]+comb[i-1][k-1])%MOD;
        }
        ll ans = 0;
        forn(x,N+1) forn(y,N-x+1) {
            ll aux = (dp[x][P1]*dp[y][P2])%MOD;
            aux = (aux*comb[N][x])%MOD;
            aux = (aux*comb[N-x][y])%MOD;
            //~ cout << x << " " << aux << endl;
            ans = ( ans + aux ) % MOD;
        }
        cout << ans << endl;

    }
    return 0;
}