#include <bits/stdc++.h>
using namespace std;
#define all(v) v.begin(), v.end()
typedef long long ll;
const int NMAX = 2e3 + 5;
const ll mod = 1e9 + 7;
ll n, s, f, dp[NMAX][NMAX], chk;
int main(void){
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n >> s >> f;
dp[0][0] = 1;
for(int i = 1; i <= n; i++)
for(int j = 1; j <= i; j++){
if(i == s || i == f) dp[i][j] = dp[i - 1][j - 1] + dp[i - 1][j];
else dp[i][j] = dp[i - 1][j - 1] * (j - chk) + dp[i - 1][j + 1] * j;
dp[i][j] %= mod;
}
cout << dp[n][1];
return 0;
}
