#include <bits/stdc++.h>
using namespace std;
const int mod = 1e9 + 7;
const int N = 5050;
int s[N], f[N];
int main(){
    int n, a, b, k;
    cin >> n >> a >> b >> k;
    f[a] = 1;
    for(int _t = 1;_t <= k;_t++){
        memset(s, 0, sizeof(s));
        for(int p = 1;p <= n;p++) if(p != b){
            int d = abs(p - b), x = f[p];
            int lft = max(1, p - d + 1), rit = min(n, p + d - 1);
            if(lft <= p - 1){
                s[lft] = (s[lft] + x) % mod;
                s[p] = (s[p] - x + mod) % mod;
            }
            if(p + 1 <= rit){
                s[p + 1] = (s[p + 1] + x) % mod;
                s[rit + 1] = (s[rit + 1] - x + mod) % mod;
            }
        }
        for(int i = 1;i <= n;i++) f[i] = (f[i - 1] + s[i]) % mod;
        f[b] = 0;
    }
    int res = 0;
    for(int i = 1;i <= n;i++) res = (res + f[i]) % mod;
    cout << res << endl;
    return 0;
}