import java.util.Scanner;
// 1:无需package
// 2: 类名必须Main, 不可修改
public class Main {
static int[][] arr = new int[4][5];
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
//在此输入您的代码...
System.out.println(dfs(0,0));
scan.close();
}
public static int dfs(int x,int y){
if (x==3||y==4){
return 1;
}else {
return dfs(x+1,y)+dfs(x,y+1);
}
}
}