#include<iostream>
#include<cstring>
#include<algorithm>
using namespace std;
const int N = 5e3 + 5, mod = 1e9 + 7;

int dp[N][N];

void solve(){
    int n, a, b, k;
    cin >> n >> a >> b >> k;
    dp[0][a] = 1;
    for(int i = 1; i <= k; i++){
        for(int j = 1; j <= n; j++){
            int dis = abs(j - b);
            int l = max(1, j - dis + 1), r = min(n, j + dis - 1);
            dp[i][l] = (dp[i][l] + dp[i - 1][j]) % mod;
            dp[i][j] = (dp[i][j] - dp[i - 1][j] + mod) % mod;
            dp[i][j + 1] = (dp[i][j + 1] + dp[i - 1][j]) % mod;
            dp[i][r + 1] = (dp[i][r + 1] - dp[i - 1][j] + mod) % mod;
        }
        for(int j = 1; j <= n; j++) dp[i][j] = (dp[i][j - 1] + dp[i][j]) % mod;
    }
    int ans = 0;
    for(int i = 1; i <= n; i++) ans = (ans + dp[k][i]) % mod;
    cout << ans << '\n';
}

int main(){
    int t = 1;
    //cin >> t;
    while(t--){
        solve();
    }
    return 0;
}