#include <cstdio>#include <cstring>#include <algorithm>#include <queue>#include <stack>#include <map>#include <set>#include <climits>#include <iostream>#include <string>using namespace std; #define MP make_pair#define PB push_back#define lson rt << 1, l, mid#define rson rt << 1 | 1, mid + 1, rtypedef long long LL;typedef unsigned long long ULL;typedef vector<int> VI;typedef pair<int, int> PII;typedef pair<double, double> PDD;const int INF = INT_MAX / 3;const double eps = 1e-8;const double DINF = 1e60;const int maxn = 5005;const LL mod = 1e9 + 7;int n, a, b, k;int f[maxn][maxn], sum[maxn][maxn];int lbd[maxn], rbd[maxn];int mabs(int x) {    return x < 0 ? -x : x;}int main() {    cin >> n >> a >> b >> k;    for(int i = 1; i <= n; i++) {        lbd[i] = INF; rbd[i] = -INF;    }    for(int i = 1; i <= n; i++) {        for(int j = 1; j <= n; j++) {            if(mabs(j - i) < mabs(j - b)) {                lbd[i] = min(lbd[i], j);                rbd[i] = max(rbd[i], j);            }        }    }    lbd[b] = rbd[b] = b;    f[0][a] = 1;    for(int i = 1; i <= n; i++) sum[0][i] = sum[0][i - 1] + f[0][i];    for(int i = 1; i <= k; i++) {        for(int j = 1; j <= n; j++) {            int l = lbd[j], r = rbd[j];            f[i][j] = (sum[i - 1][r] - sum[i - 1][l - 1] + mod) % mod;            if(lbd[j] <= j && rbd[j] >= j)                 f[i][j] = (f[i][j] - f[i - 1][j] + mod) % mod;        }        for(int j = 1; j <= n; j++)             sum[i][j] = (sum[i][j - 1] + f[i][j]) % mod;    }    cout << sum[k][n] << endl;    return 0;}