#include<bits/stdc++.h>
using namespace std;
#define int long long 
int n,a,b,k;
const int mod = 1e9+7;
int f[5005][5005];
int pre[5005];

signed main(){
    cin>>n>>a>>b>>k;
    f[a][0]=1;
    for(int i=1;i<=n;++i)pre[i]=(pre[i-1]+f[i][0])%mod;
    for(int K=1;K<=k;++K){
        for(int i=1;i<=n;++i){
            if(i==b)continue;
            if(i<b)f[i][K]=pre[i-1];
            else f[i][K]=(pre[n]-pre[i]+mod)%mod;
            int d=abs(b-i)-1;
            d/=2;
            if(i<b)f[i][K]=(f[i][K]+pre[i+d]-pre[i]+mod)%mod;
            else f[i][K]=(f[i][K]+pre[i-1]-pre[i-1-d]+mod)%mod;
        }
        for(int i=1;i<=n;++i)pre[i]=(pre[i-1]+f[i][K])%mod;
    }
    printf("%d\n",pre[n]);
    return 0;
}