#include <stdio.h>
int num(int x,int y)
{
    if(y==0) return 1;
    else if(x==1&&y>=0&&y<=9) return 1;
    else if(y>=10) return num(x-1,y)+num(x,y-1)-num(x-1,y-10);
    else return num(x-1,y)+num(x,y-1);
}
int main()
{
    int n,i,j,sum=0;
    scanf("%d",&n);
    i=n/2;
    for(j=0;j<=9*i;j++)
        sum+=num(i,j)*num(i,j);
    printf("%d\n",sum);
    return 0;
}

数据严重出错啊= =