#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
using namespace std;
using namespace __gnu_pbds;
#define endl "\n"
#define ll long long
#define IOS ios_base::sync_with_stdio(false); cin.tie(nullptr);
const int N = 2005;
const long long M = 1e9 + 7;
long long dp[N][N];
int main() {
IOS;
int n, l, r;
cin >> n >> l >> r;
dp[1][1] = 1;
for (int i = 2; i <= n; i++) {
for (int j = 1; j < i; j++) {
if (i == l || i == r) {
dp[i][j + 1] = (dp[i][j + 1] + dp[i - 1][j]) % M;
dp[i][j] = (dp[i][j] + dp[i - 1][j]) % M;
} else {
dp[i][j + 1] = (dp[i][j + 1] + dp[i - 1][j] * (j - 1)) % M;
if (i < l) {
dp[i][j + 1] = (dp[i][j + 1] + dp[i - 1][j]) % M;
}
if (i < r) {
dp[i][j + 1] = (dp[i][j + 1] + dp[i - 1][j]) % M;
}
dp[i][j - 1] = (dp[i][j - 1] + dp[i - 1][j] * (j - 1)) % M;
}
}
}
cout << dp[n][1];
return 0;
}
