#include <bits/stdc++.h>

using namespace std;

const int MAX_N = 5000 + 5;
const int P = 1000000007;

int N, K, A, B;
int f[MAX_N], g[MAX_N];

int main() {
    scanf("%d%d%d%d", &N, &A, &B, &K);
    f[A] = 1;
    for (int i = 1; i <= K; i ++) {
        for (int j = 1; j <= N; j ++) {
            if (j == B) continue;
            int l = max(1, j - abs(j - B) + 1);
            int r = min(N, j + abs(j - B) - 1);
            g[l] += f[j];
            g[l] -= g[l] >= P ? P : 0;
            g[r + 1] -= f[j];
            g[r + 1] += g[r + 1] < 0 ? P : 0;
        }
        for (int j = 1, t = 0; j <= N; j ++) {
            t += g[j], g[j] = 0;
            t -= t >= P ? P : 0;
            f[j] = t - f[j];
            f[j] += f[j] < 0 ? P : 0;
        }
        f[B] = 0;
    }
    A = 0;
    for (int j = 1; j <= N; j ++) {
        A += f[j];
        A -= A >= P ? P : 0;
    }
    printf("%d\n", A);
    return 0;
}