#include <bits/stdc++.h>
#define ll long long
#define ld long double
using namespace std;
const int mxN=2e3, MOD=1e9+7;
// solve problem (no tutorial)
// take at least 15 mins explaining solution to yourself
ll dp[mxN+5][2][mxN+5];
void go(){
ll n, cs, cf;
cin >> n >> cs >> cf;
for(int i=n; i>=1; i--){
for(int j=0; j<2; j++){
for(int k=0; k<=n; k++){
ll &ret = dp[i][j][k];
if(i == n){
ret = 1;
continue;
}
if(j == 0){
ret = dp[i+1][1][k-1];
}
else{
ll len = (n-(i-1)-k)-1;
ret = dp[i+1][0][min(n, k+len-1)];
if(k-1 >= 0){
ret = (ret - dp[i+1][0][k] + MOD)%MOD;
}
}
}
for(int k=1; k<=n; k++){
dp[i][j][k] = (dp[i][j][k] + dp[i][j][k-1])%MOD;
}
}
}
ll ans = (dp[2][0][n-cs-(cf > cs)] + dp[2][1][n-cs-(cf > cs)])%MOD;
cout << ans;
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
int tc=1;
// cin >> tc;
while(tc--){
go();
}
}
