#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define run ios_base::sync_with_stdio(false);cin.tie(0);
#define ll long long
#define pll pair<ll, ll>
#define ull unsigned ll
#define ld double
#define endl "\n"
#define pb push_back
#define fi first
#define se second
#define pi acos(-1)
#define N 2007
#define minimum -9223372036854775807
#define maximum -minimum
#define mod 1000000007
using namespace std;
using namespace __gnu_pbds;
template <class t>
using ordered_set=tree<t, null_type,less_equal<t>, rb_tree_tag,tree_order_statistics_node_update>;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
ll gcd(ll a, ll b)
{
if(b==0)
return a;
return gcd(b, a%b);
}
ll lcm(ll a, ll b)
{
return a/gcd(a, b)*b;
}
bool isprime(ll n)
{
if(n==1)
return 0;
for(ll i=2; i*i<=n; i++)
{
if(n%i==0)
return 0;
}
return 1;
}
ll binpow(ll a, ll b)
{
a%=mod;
ll res=1;
while(b>0)
{
if(b%2==1)
res=(res*a)%mod;
a=(a*a)%mod;
b/=2;
}
return res;
}
ll dp[N][N];
int main()
{
run;
ll n, cs, cf, fixed=0;
cin>>n>>cs>>cf;
dp[1][1]=1;
for(ll i=2; i<=n; i++)
{
fixed=0;
if(i>cs)
fixed++;
if(i>cf)
fixed++;
for(ll j=1; j<=i; j++)
{
if(i==cs || i==cf)
{
dp[i][j]=((dp[i][j]+dp[i-1][j-1])%mod+dp[i-1][j])%mod;
}
else
{
dp[i][j]=(dp[i][j]+(dp[i-1][j+1]*j)%mod)%mod;
dp[i][j]=(dp[i][j]+(dp[i-1][j-1]*(j-fixed))%mod)%mod;
}
}
}
cout<<dp[n][1]<<endl;
}
// By Xanlar
