#include "bits/stdc++.h"
using namespace std;
#define int long long
const int MAXN = 2023;
const int MOD = 1e9 + 7;
int dp[MAXN][MAXN], n, a, b;
int32_t main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n >> a >> b;
if(a > b) swap(a, b);
dp[1][1] = 1;
for(int i=2; i<=n; i++) {
for(int j=1; j<=n; j++) {
if(i == a || i == b) {
dp[i][j] = (dp[i-1][j-1] + dp[i-1][j]) % MOD;
}
else if(i < a) {
dp[i][j] = (j * dp[i-1][j-1] + j * dp[i-1][j+1]) % MOD;
}
else if(a < i && i < b) {
dp[i][j] = ((j-1) * dp[i-1][j-1] + j * dp[i-1][j+1]) % MOD;
}
else {
dp[i][j] = (max(0ll, j-2) * dp[i-1][j-1] + j * dp[i-1][j+1]) % MOD;
}
}
}
cout << dp[n][1] << "\n";
}
