#include <stdio.h>
#include <stdlib.h>

#define MAX	100

int h[MAX];		/* seznam hran */
int l[MAX];
int N;

int cmp(const void *a, const void *b)
{
  return *(int *) b - *(int *) a;
}

int p[MAX];

int solve(int v)
{
  int i, j, max=0;

  if (l[v] == l[v+1])		/* list */
    return 1;

  for (i=l[v]; i<l[v+1]; i++)	/* synove */
    p[i] = solve(h[i]);

  qsort(p+l[v], l[v+1]-l[v], sizeof(*p), cmp);

  for (i=1; i<=l[v+1]-l[v]; i++) {
    j = i+l[v]-1;
    if (p[j] + i > max)		/* maximum */
      max = p[j] + i;
  }
  
  return max;
}

int main(void)
{
  int i, j, x, y, z, koren;
  
  /* hrany jsou na vstupu setrideny */
  scanf("%d %d", &N, &koren);
  koren--;
  for (i=j=0, z=-1; i<N-1; i++) {
    scanf("%d %d", &x, &y);
    x--, y--;
    if (y!=z) { z=y; l[y]=j; }
    h[j] = x;
    j++;
  }
  for (y++; y<=N; y++)
    l[y]=j;

  printf("Potrebujeme alespon %d kamenu.\n", solve(koren));
  return 0;
}