#include <bits/stdc++.h>
using namespace std;
using i64 = long long;
const int Z = 2e3+2;
const i64 MOD = 1e9+7;
inline int mul(const i64 &x, const i64 &y) {
return (x * y) % MOD;
}
inline int add(int x, const int &y) {
if((x += y) >= MOD) x -= MOD;
return x;
}
int N, cs, cf, dp[Z] {1}, prv[Z];
int main() {
cin >> N >> cs >> cf;
for(int i = 1; i <= N; ++i) {
copy(dp, dp + Z, prv);
dp[0] = 0;
if(i == cs || i == cf) {
for(int j = 1; j <= N; ++j)
dp[j] = add(prv[j-1], prv[j]);
} else {
for(int j = 1; j <= N; ++j)
dp[j] = add(mul(prv[j+1], j), mul(prv[j-1], j - (i > cs) - (i > cf)));
}
}
cout << dp[1];
}
