#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const ll MOD = 1e9 + 7;
int n, s, f;
ll dp[2002][2002];
int main() {
cin >> n >> s >> f;
dp[1][1] = 1;
for (int i = 2; i <= n; ++i) {
if (i == s or i == f) {
for (int j = 1; j <= n; ++j) {
dp[i][j] = (dp[i][j] + dp[i - 1][j - 1]) % MOD;
dp[i][j] = (dp[i][j] + dp[i - 1][j]) % MOD;
}
} else {
for (int j = 1; j <= n; ++j) {
dp[i][j] = (dp[i][j] + dp[i - 1][j - 1] * (j - (i > s) - (i > f))) % MOD;
dp[i][j] = (dp[i][j] + dp[i - 1][j + 1] * j) % MOD;
}
}
}
cout << dp[n][1] << endl;
}
