#include <cstring>
#include <iostream>
using namespace std;

const int MAXN = 300 + 5;

typedef struct {
  int left, right;
  int score;
} node;

node tree[MAXN];
int mem[MAXN][MAXN];
int N, M;

void insert(int current, int head) {
  tree[current].right = tree[head].left;
  tree[head].left = current;
}

int dfs(int node, int slots) {
  if (node < 0 || !slots) {
    return 0;
  } else if (!node) { // Root node
    return dfs(tree[node].left, slots);
  }

  if (mem[node][slots] > -1) {
    return mem[node][slots];
  }
  mem[node][slots] = dfs(tree[node].right, slots); // When ignore this node
  for (int i = 1; i <= slots; i++) {
    int other = dfs(tree[node].left, i - 1) + dfs(tree[node].right, slots - i) +
                tree[node].score;
    mem[node][slots] = max(mem[node][slots], other);
  }
  return mem[node][slots];
}

int main() {
  // Init
  cin >> N >> M;
  memset(tree, -1, sizeof tree);
  memset(mem, -1, sizeof mem);
  for (int i = 1; i <= N; i++) {
    int depends, c;
    cin >> depends >> c;
    insert(i, depends);
    tree[i].score = c;
  }
  // Calculating!
  printf("%d", dfs(0, M));
}