#include <bits/stdc++.h>
using namespace std;
 
int main() 
{
	int n,x,y; cin>>n>>x>>y;
	int f[n][n];
	f[0][1]=1;f[1][0]=1;f[0][2]=2;f[2][0]=2;f[1][2]=5;f[2][1]=5;
 
	for (int i=2; i<=x-1; i++)
	for (int j=2; j<=y-1; j++)
	f[i][j]=f[i-1][j]+f[i-2][j]+f[j-1][i]+f[j-2][i];
 
	cout<< f[y][x];
 
	return 0;
}