import java.util.Scanner;
// 1:无需package
// 2: 类名必须Main, 不可修改
public class Main {
static int ans = 0;
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
int i = 0;
int j = 0;
dfs(i,j);
System.out.println(ans);
scan.close();
}
private static int dfs(int i,int j)
{
if(i==3||j==4)
{
return ans = ans + 1;
}
else
{
return dfs(i+1,j)+dfs(i,j+1);
}
}
}