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

typedef struct Edge {
    int to;
    int weight;
    struct Edge* next;
} edge;

typedef struct {
    int now;
    int distance;
} tuple;

void add_edge(edge** graph, int u, int v, int w);
tuple find_maxLength_node(int start, edge** graph, int v);

int main() {
    int V;
    scanf("%d",&V);

    edge** graph = (edge**)malloc(sizeof(edge*)*(V+1));

    for(int i=0; i<V; i++) {
        int u;
        scanf("%d",&u);
        graph[u] = NULL;

        while(1) {
            int v;
            scanf("%d",&v);
            if(v==-1) break;

            int w;
            scanf("%d",&w);

            add_edge(graph,u,v,w);
        }
    }

    int start = find_maxLength_node(1, graph, V).now;
    int radius = find_maxLength_node(start, graph, V).distance;
    printf("%d\n",radius);



    for(int i = 1; i <= V; i++) {
        edge* ptr = graph[i];
        while(ptr != NULL) {
            edge* temp = ptr;
            ptr = ptr->next;
            free(temp);
        }
    }

    free(graph);
    return 0;
}

void add_edge(edge** graph, int u, int v, int w) {
    edge* new_edge = (edge*)malloc(sizeof(edge));
    new_edge -> to = v;
    new_edge -> weight = w;
    new_edge -> next = graph[u];
    graph[u] = new_edge;
}

tuple find_maxLength_node(int start, edge** graph, int v) {
    tuple result = {start, 0};
    bool* visited = (bool*)calloc(v+1,sizeof(bool));
    tuple* stack = (tuple*)malloc(sizeof(tuple)*v);
    int top = -1;

    stack[++top] = result;
    visited[start] = true;

    while(top != -1) {
        tuple current = stack[top--];

        if(result.distance < current.distance) result = current;

        edge* ptr = graph[current.now];
        while(ptr != NULL) {
            if(!visited[ptr->to]) {
                tuple next = {ptr->to, ptr->weight + current.distance};
                stack[++top] = next;
                visited[ptr->to] = true;
            }
            ptr = ptr -> next;
        }
    }

    free(visited);
    free(stack);
    return result;
}