#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
const ll MOD = 1e9 + 7;
int n, cs, cf;
ll dp[2005][2005];
ll solve(int i, int k) {
if (k < 0) return 0ll;
if (i > n) return k == 1;
if (dp[i][k] != -1) return dp[i][k];
ll& ans = dp[i][k];
ans = 0;
if (i == cs || i == cf) {
ll op1 = solve(i + 1, k);
ll op2 = solve(i + 1, k + 1);
return ans = (op1 + op2) % MOD;
}
if (i < cs) {
ll op1 = (1ll * (k - 1) * solve(i + 1, k - 1)) % MOD;
ll op2 = (1ll * (k + 1) * solve(i + 1, k + 1)) % MOD;
return ans = (op1 + op2) % MOD;
}
if (i < cf) {
ll op1 = (1ll * (k - 1) * solve(i + 1, k - 1)) % MOD;
ll op2 = (1ll * k * solve(i + 1, k + 1)) % MOD;
return ans = (op1 + op2) % MOD;
}
ll op1 = (1ll * (k - 1) * solve(i + 1, k - 1)) % MOD;
ll op2 = (1ll * (k - 1) * solve(i + 1, k + 1)) % MOD;
return ans = (op1 + op2) % MOD;
}
int main(){
ios::sync_with_stdio(false);
cin.tie(0);
cin >> n >> cs >> cf;
if (cs > cf) swap(cs, cf);
memset(dp, -1, sizeof dp);
cout << solve(1, 0) << '\n';
return 0;
}
