#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) {
// If the current number is the start or end point:
// 1. It can start a new component (at either end of the sequence)
// 2. It can be added to an existing component
dp[i][j] = (dp[i - 1][j - 1] + dp[i - 1][j]) % MOD;
} else {
// If it's a regular number:
// 1. Create a new component: dp[i-1][j-1] * (number of available slots)
// Available slots = j - (is i > cs) - (is i > cf)
long long choices_new = j;
if (i > cs) choices_new--;
if (i > cf) choices_new--;
// 2. Merge two existing components: dp[i-1][j+1] * j
long long choices_merge = j;
dp[i][j] = (dp[i - 1][j - 1] * choices_new + dp[i - 1][j + 1] * choices_merge) % MOD;
}
}
}
// The answer is the state where all N numbers are used and they form 1 single connected path.
cout << dp[N][1] << endl;
return 0;
}
