#include <iostream>
#include <vector>
using namespace std;
long long dp[2005][2005];
const int MOD = 1000000007;
int main() {
int N, cs, cf;
if (!(cin >> N >> cs >> cf)) return 0;
dp[0][0] = 1;
for (int i = 1; i <= N; i++) {
for (int j = 1; j <= i; j++) {
if (i == cs || i == cf) {
dp[i][j] = (dp[i - 1][j - 1] + dp[i - 1][j]) % MOD;
} else {
long long choices_to_add = j - (i > cs) - (i > cf);
long long add = (dp[i - 1][j - 1] * choices_to_add) % MOD;
long long combine = (dp[i - 1][j + 1] * j) % MOD;
dp[i][j] = (add + combine) % MOD;
}
}
}
cout << dp[N][1] << endl;
return 0;
}
