#include <iostream>
#include <cstdio>
using namespace std;

typedef long long ll;
const int N = 5010, mod = 1e9 + 7;
ll f[N][N], n, a, b, K, s[N];

#define myabs(x) ((x) > 0 ? (x) : -(x))
ll get(ll l, ll r) {
    if(l > r) return 0;
    return ((s[r] - s[l - 1]) % mod + mod) % mod;
}

int main() {
    scanf("%lld%lld%lld%lld", &n, &a, &b, &K);
    f[0][a] = 1;
    for (int i = 1; i <= n; i++) s[i] = (s[i - 1] + f[0][i]) % mod;
    for (int k = 1; k <= K; k++) {
        for (int i = 1; i <= n; i++) {
            if(i == b) continue;
            int l, r;
            if(i < b) l = 1, r = (i + b + 1) / 2 - 1;
            else l = (i + b) / 2 + 1, r = n;
            f[k][i] = (get(l, i - 1) + get(i + 1, r)) % mod;
        }
        for (int i = 1; i <= n; i++) s[i] = (s[i - 1] + f[k][i]) % mod;
    }
//    for (int i = 1; i <= K; i++) {
//        for (int j = 1; j <= n; j++) cout << f[i][j] << ' ';
//        cout << '\n';
//    }
    printf("%lld\n", s[n]);
    return 0;
}