#include <bits/stdc++.h>

using namespace std;

#define int long long
// #define x first
// #define y second
#define File(a) freopen(a".in", "r", stdin), freopen(a".out", "w", stdout)

inline void debug() { cerr << '\n'; }
template<typename Type, typename... Other>
inline void debug(const Type& x, const Other&... y) { cerr << x << ' '; debug(y...); }
#define DEBUG(a...) cerr << "[" << #a << "] = ", debug(a);

typedef long long LL;
typedef pair<int, int> PII;

const int N = 5010;
const int INF = 0x3f3f3f3f;
const int mod = 1000000007;

template<typename Type>
inline void read(Type &res)
{
    res = 0;
    int ch = getchar(), flag = 0;
    while (!isdigit(ch)) flag |= ch == '-', ch = getchar();
    while (isdigit(ch)) res = (res << 3) + (res << 1) + (ch ^ 48), ch = getchar();
    res = flag ? -res : res;
}
template<typename Type, typename... Other>
inline void read(Type &res, Other&... y) { read(res), read(y...); }

int n, st, ed, k;
int f[N][N], sum[N][N];

namespace BF
{
    void solve()
    {
        f[0][st] = 1;
        for (int i = 0; i < k; i ++)
        {
            for (int j = 1; j <= n; j ++)
            {
                if (j == ed) continue;
                if (j < ed)
                {
                    for (int t = max(1LL, j - (ed - j) + 1); t < ed; t ++)
                        if (t != j) f[i + 1][t] = (f[i + 1][t] + f[i][j]) % mod;
                }
                else
                {
                    for (int t = ed + 1; t <= min(n, j + j - ed - 1); t ++)
                        if (t != j) f[i + 1][t] = (f[i + 1][t] + f[i][j]) % mod;
                }
            }
        }
        int ans = 0;
        for (int i = 1; i <= n; i ++) ans = (ans + f[k][i]) % mod;
        cout << ans << '\n';
    }
}

signed main()
{
    read(n, st, ed, k);
    // if (n <= 500) BF::solve();
    
    f[0][st] = 1;
    for (int i = st; i <= n; i ++) sum[0][i] = 1;

    for (int i = 1; i <= k; i ++)
    {
        for (int j = 1; j <= n; j ++)
        {
            // if (j == ed) continue;
            if (j < ed)
            {
                int cur = j + ed - 1 >> 1;
                f[i][j] = (sum[i - 1][cur] - f[i - 1][j] + mod) % mod;
            }
            else if (j > ed)
            {
                int cur = j + ed + 2 >> 1;
                f[i][j] = (sum[i - 1][n] - sum[i - 1][cur - 1] - f[i - 1][j] + 2 * mod) % mod;
            }
            sum[i][j] = (sum[i][j - 1] + f[i][j]) % mod;
            // DEBUG(i, j, f[i][j], sum[i][j]);
        }
    }
    cout << sum[k][n] << '\n';

    return 0;
}