#include <bits/stdc++.h>
using namespace std;
//@formatter:off
using ll = long long;
template<typename T> istream &operator>>(istream &is, vector<T> &a);
template<typename T> ostream &operator<<(ostream &os, vector<T> &a);
//@formatter:on
#define int long long
const int mod = 1e9 + 7;
signed main() {
#ifdef LOCAL
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#else
ios_base::sync_with_stdio(false);
cin.tie(0);
#endif
int n, a, b;
cin >> n >> a >> b;
a--, b--;
vector<vector<int>> dp(n + 1, vector<int>(n + 1));
dp[0][0] = 1;
for (int i = 0; i < n; ++i) {
for (int comp = 0; comp < n; ++comp) {
if (i == a || i == b) {
dp[i + 1][comp + 1] += dp[i][comp];
dp[i + 1][comp] += dp[i][comp];
dp[i + 1][comp + 1] %= mod;
dp[i + 1][comp] %= mod;
} else {
dp[i + 1][comp + 1] += dp[i][comp] * (comp + 1 - (a <= i) - (b <= i));
if (comp > 0)dp[i + 1][comp - 1] += dp[i][comp] * (comp - 1);
dp[i + 1][comp + 1] %= mod;
dp[i + 1][comp - 1] %= mod;
}
}
}
cout << dp[n][1] << "\n";
}
// region POZOR
template<typename T>
ostream &operator<<(ostream &os, vector<T> &a) {
for (int i = 0; i < a.size(); i++)
os << a[i] << " \n"[i == a.size() - 1];
return os;
}
template<typename T>
istream &operator>>(istream &is, vector<T> &a) {
for (auto &i: a)
is >> i;
return is;
}
// endregion
