#include <stdio.h>

int pf[] = { 5, 8, -1, -1, 3, 7, -1, 10, -1, -1 };
int fd[] = { -1, -1, 4, -1, 6, 2, -1, -1, -1, 9 };

int fct(int radacina){

	int y = 1;

	int x = pf[radacina - 1];
	if (pf[radacina] == -1){
		y = 0;
		printf("%d", y);
		return y;
	}

	while (x != -1){
		x = fd[x-1];
		y++;

	}

	return y;
}

int main(){
	int j;
	int max = fct(0);
	for (j = 1; j < 10; j++){
		if (fct(j) > max){
			max = fct(i);
		}
	}
	printf("%d", max);
}