#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int MxN = 2020;
const ll MOD = 1e9 + 7;
ll dp[MxN][MxN]; // dp(i, j) = 1 to i with j components
signed main() {
cin.tie(nullptr)->ios::sync_with_stdio(false);
int n, stp, edp;
cin >> n >> stp >> edp;
dp[1][1] = 1ll;
for(int i=2; i<=n; ++i) {
for(ll j=1; j<=(ll) i; ++j) {
if(i == stp || i == edp) {
dp[i][j] = (dp[i - 1][j - 1] + dp[i - 1][j]) % MOD;
}
else {
ll r = j;
if(i > stp) {
r -= 1ll;
}
if(i > edp) {
r -= 1ll;
}
dp[i][j] = (dp[i - 1][j - 1] * r) % MOD;
dp[i][j] = (dp[i][j] + (dp[i - 1][j + 1] * j)) % MOD;
}
}
}
cout << dp[n][1] << "\n";
return 0;
}
