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Codeforces Alpha Round #20 (Codeforces format)

You are given a weighted undirected graph. The vertices are enumerated from 1 to n. Your task is to find the shortest path between the vertex 1 and the vertex n.

Input

The first line contains two integers n and m (2 ≤ n ≤ 105, 0 ≤ m ≤ 105), where n is the number of vertices and m

 is the number of edges. Following m lines contain one edge each in form aibi and wi (1 ≤ ai, bi ≤ n, 1 ≤ wi ≤ 106), where ai, bi are edge endpoints and wi is the length of the edge.

It is possible that the graph has loops and multiple edges between pair of vertices.

Output

Write the only integer -1 in case of no path. Write the shortest path in opposite case. If there are many solutions, print any of them.

Examples

input

5 6
1 2 2
2 5 5
2 3 4
1 4 1
4 3 3
3 5 1

output

1 4 3 5 

input

5 6
1 2 2
2 5 5
2 3 4
1 4 1
4 3 3
3 5 1

output

1 4 3 5 
#include <bits/stdc++.h>
#define INF 0x3fffffff
#define mem(ar,num) memset(ar,num,sizeof(ar))
#define me(ar) memset(ar,0,sizeof(ar))
#define lowbit(x) (x&(-x))
#define IOS ios::sync_with_stdio(false)
#define DEBUG cout<<endl<<"DEBUG"<<endl;
using namespace std;
int n,m,head[100100],a,b,c,cnt,flag;
long long dis[100100];int vis[100100],po[100100],ans[100100];
struct no{
    int next,to,w;
}edge[500100*2];
void add(int u,int v,int w){
    edge[++cnt].next=head[u];
    edge[cnt].to=v;
    edge[cnt].w=w;
    head[u]=cnt;
}
struct node{
    int dis;
    int pos;
    bool operator <( const node &x )const{
        return x.dis < dis;
    }
};
bool dijkstra(){
    priority_queue<node> q;
    dis[1]=0;
    ans[flag]=1;
    q.push((node){0,1});
    while(!q.empty()){
        node tmp = q.top();
        q.pop();
        int x = tmp.pos, d = tmp.dis;
        if(vis[x])
            continue;
        vis[x] = 1;
        int t=head[x];
        while(t){
            int y=edge[t].to;
            if(dis[y] > dis[x] + edge[t].w){
                dis[y] = dis[x] + edge[t].w;
                if(!vis[y]){
                    po[edge[t].to]=tmp.pos;//記錄路徑
                    q.push((node){dis[y],y});
                }
            }
            t=edge[t].next;
        }
    }
    if(dis[n]==0x7f7f7f7f7f7f7f7f)return false;
    return true;
}
int main(){
    mem(dis,0x7f);
    cin>>n>>m;
    for(int i=0;i<m;i++){
        cin>>a>>b>>c;
        add(a,b,c);
        add(b,a,c);
    }
    if(dijkstra()){
        for(int i=n;i;i=po[i]){
            ans[++flag]=i;
        }
        for(int i=flag;i>=1;i--)
            cout<<ans[i]<<" ";
    }else cout<<-1<<endl;
    return 0;
}