#include <bits/stdc++.h>
using namespace std;
#define f first
#define s second
typedef long long ll;
typedef pair<int, int> pi;
const ll mod = 1e9+7;
int main(){
ios_base::sync_with_stdio(0); cin.tie(0);
int n, cs, cf; cin >> n >> cs >> cf;
ll dp[n+1][n+1];
for(int i = 0; i <= n; i++)
for(int j = 0; j <= n; j++)
dp[i][j] = 0;
dp[1][1] = 1;
for(int i = 2; i <= n; i++){
for(ll j = 1; j <= n-1; j++){
if(i == cs || i == cf){
dp[i][j] = dp[i-1][j] + dp[i-1][j-1];
if(dp[i][j] >= mod) dp[i][j] -= mod;
}else{
dp[i][j] = j*dp[i-1][j+1] + (j - (ll)(i > cs) - (ll)(i > cf))*dp[i-1][j-1];
dp[i][j] %= mod;
}
}
}
cout << dp[n][1] << "\n";
}
