# include <stdio.h>
# include <stdlib.h>
# include <iostream>
# include <string.h>
# include <math.h>
using namespace std;

# define IL inline
# define RG register
# define UN unsigned
# define ll long long
# define rep(i, a, b) for(RG int i = a; i <= b; i++)
# define per(i, a, b) for(RG int i = b; i >= a; i--)
# define uev(e, u) for(RG int e = ft[u]; e != -1; e = edge[e].nt)
# define mem(a, b) memset(a, b, sizeof(a))
# define max(a, b) ((a) > (b)) ? (a) : (b)
# define min(a, b) ((a) < (b)) ? (a) : (b)

IL int Get(){
    RG char c = '!'; RG int num = 0, z = 1;
    while(c != '-' && (c > '9' || c < '0')) c = getchar();
    if(c == '-') z = -1, c = getchar();
    while(c >= '0' && c <= '9') num = num * 10 + c - '0', c = getchar();
    return num * z;
}

const int MAXN = 302, INF = 2147483647;
struct Edge{
    int to, nt;
} edge[MAXN << 1];
int n, m, ft[MAXN], cnt, in[MAXN], w[MAXN], f[MAXN][MAXN];

IL void DP(RG int u){
    rep(i, 1, m) f[u][i] = w[u];
    uev(e, u){
        RG int v = edge[e].to;
        DP(v);
        per(i, 2, m)
            per(j, 1, i - 1)
                f[u][i] = max(f[u][i], f[u][j] + f[v][i - j]);
    }
}

int main(){
    mem(ft, -1);
    n = Get(); m = Get() + 1;
    rep(i, 1, n){
        RG int v = Get(); w[i] = Get();
        if(!v) continue;
        edge[cnt] = (Edge){i, ft[v]}; ft[v] = cnt++;
        in[i]++;
    }
    rep(i, 1, n) if(!in[i]) edge[cnt] = (Edge){i, ft[n + 1]}, ft[n + 1] = cnt++;
    DP(n + 1);
    printf("%lld\n", f[n + 1][m]);
    return 0;
}