#include<bits/stdc++.h>
using namespace std;

const int maxn=2005;
const int mod=1e9+7;

inline int read(){
    int x=0,w=1;char c=getchar();
    while(c<'0'||c>'9'){if(c=='-')w=-1;c=getchar();}
    while(c<='9'&&c>='0'){x=(x<<3)+(x<<1)+c-'0';c=getchar();}
    return x*w;
}

int n,s,t;
int f[maxn][maxn];

int main(){
    n=read(),s=read(),t=read();
    f[0][0]=1;
    for(int i=1;i<=n;++i){
        for(int j=1;j<=i;++j){
            if(i!=s&&i!=t){
                f[i][j]=(1ll*(j-(i>s)-(i>t))*f[i-1][j-1]+1ll*j*f[i-1][j+1])%mod;
            }
            else{
                f[i][j]=(f[i-1][j-1]+f[i-1][j])%mod;
            }
        }
    }
    printf("%d\n",f[n][1]);
    return 0;
}