#include <iostream>
using namespace std;
const int N = 45, mod = 1e9 + 7;
int A[N][N][N], D[N][N][N];
void precompute(){
A[2][1][2] = D[2][2][1] = 1;
for (int i=3;i<N;i++){
// cout<<i<<endl;
for (int j=1;j<i;j++){
for (int k=j+1;k<=i;k++){
for (int l=j;l<i;l++)
A[i][j][k] = (A[i][j][k] + D[i-1][l][k-1]) % mod;
}
}
for (int j=1;j<=i;j++){
for (int k=j+1;k<=i;k++){
for (int l=1;l<j;l++)
D[i][j][k] = (D[i][j][k] + A[i-1][l][k-1]) % mod;
}
}
for (int j=1;j<=i;j++){
for (int k=j+1;k<=i;k++){
if (i % 2 == 1)
A[i][k][j] = A[i][j][k], D[i][k][j] = D[i][j][k];
else
A[i][k][j] = D[i][j][k], D[i][k][j] = A[i][j][k];
// if (i == 4)
// cout<<j<<" "<<k<<" "<<A[i][j][k]<<" "<<D[i][j][k]<<'\n';
}
}
}
}
int main(){
precompute();
int n, s, t;
cin>>n>>s>>t;
if (s > t)
swap(s, t);
cout<<(A[n][s][t] + D[n][s][t]) % mod<<'\n';
}
