#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
#define FOR(i,a) for (int i=0;i<(a);++i)
#define FORD(i,a) for (int i=(a)-1;i>=0;i--)
#define FORT(i,a,b) for (int i=(a);i<=(b);++i)
#define FORTD(i,b,a) for (int i=(b);i>=(a);--i)
#define trav(i,v) for (auto i : v)
#define all(v) v.begin(),v.end()
#define ad push_back
#define fr first
#define sc second
#define mpr(a,b) make_pair(a,b)
#define pir pair<int,int>
#define all(v) v.begin(),v.end()
#define make_unique(v) v.erase(unique(all(v)),v.end())
#define fastio ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define dbg(x);
#define dbgv(v);
#define srng mt19937 rng(chrono::steady_clock::now().time_since_epoch().count())
#define y1 EsiHancagorcRepa
const int N=2e3+10;
const ll MOD=1e9+7;
ll x[N][N],dp[N][N],suf[N][N];
int main(){
fastio;
srng;
int n,s,f;
cin>>n>>s>>f;
if (s>f)swap(s,f);
dp[1][0]=1;
suf[1][0]=1;
FORT(i,2,n){
FOR(j,i-1){
dp[i][j]=suf[i-1][i-j-2];
//cout<<dp[i][j]<<" ";
}
dp[i][i-1]=dp[i][i-2];
//cout<<endl;
FORD(j,i){
suf[i][j]=suf[i][j+1]+dp[i][j];
suf[i][j]%=MOD;
}
}
FORT(i,1,n){
int k=i-(n-f);
if (k<=1)continue;
i--;
k--;
if (i==1 &&k==1){
x[i+1][1]=1;
}
if (k!=1 && i%2)
x[i+1][1]=dp[i-1][k-2];
if (i%2==0){
if (k==i)x[i+1][1]+=dp[i-2][0];
else x[i+1][1]+=dp[i-1][i-k-1];
}
i++;
x[i][1]%=MOD;
//cout<<x[i][1]<<" ";
}
//cout<<endl;
FORT(i,1,n){
int k=i-(n-s);
if (k<=1)continue;
x[i][2]=x[i][1]+x[i-1][1];
x[i][2]%=MOD;
//cout<<x[i][2]<<" ";
}
//cout<<endl;
FORT(i,3,n){
FORT(j,3,n){
x[n][i]=(2*x[n][i-1]-x[n][i-2]-x[n-2][i-2]+2*MOD)%MOD;
}
}
cout<<x[n][s]<<endl;
}
