#include <iostream>
#include <cstdio>
#include <cmath>
#include <queue>
#include <string.h>
using namespace std;

const int INF=0x3f3f3f3f;
const int maxm=511111;
const int maxn=111111;

struct EdgeNode
{
    int to;
    int w;
    int next;
};

EdgeNode edges[maxm];
int N,M;
int head[maxn],edge;
bool vis[maxn];
queue <int> que;
int dis[maxn];

void addedge(int u,int v,int c)
{
    edges[edge].w=c,edges[edge].to=v,edges[edge].next=head[u],head[u]=edge++;
}

void init()
{
    memset(head,-1,sizeof(head));
    edge=0;
}

void spfa(int s,int n)//單源最短路(s為起點，n為節點總數)
{
    int u;
    for (int i=0; i<=n; i++)
        dis[i]=INF;
    memset(vis,0,sizeof(vis));
    while (!que.empty()) que.pop();
    que.push(s);
    vis[s]=true;
    dis[s]=0;
    while (!que.empty())
    {
        u=que.front();
        que.pop();
        vis[u]=false;
        for (int i=head[u]; i!=-1; i=edges[i].next)
        {
            int v=edges[i].to;
            int w=edges[i].w;
            if (dis[v]>dis[u]+w)
            {
                dis[v]=dis[u]+w;
                if (!vis[v])
                {
                    vis[v]=true;
                    que.push(v);
                }
            }
        }
    }
}