#include <bits/stdc++.h>   using namespace std;   const int N = 5005;   const int mod = 1000000007;   int n, a, b, k;   int dp[N][N];   int main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     cin >> n >> a >> b >> k;     for (long long i = 1; i <= n; ++i) {       dp[0][i] = i;     }     for (int trip = 1; trip <= k; trip++) {       for (int floor = 1; floor <= n; floor++) {         int d = abs(b - floor);         dp[trip][floor] = dp[trip - 1][min(n, floor + d - 1)] -                           dp[trip - 1][max(0, floor - d)] - dp[trip - 1][floor] +                           dp[trip - 1][floor - 1];         while (dp[trip][floor] < 0) dp[trip][floor] += mod;         dp[trip][floor] %= mod;         dp[trip][floor] = (dp[trip][floor] + dp[trip][floor - 1]) % mod;       }     }     cout << (dp[k][a] - dp[k][a - 1] + mod) % mod;     return 0;   }   