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

const int MAX_M = 101;
const int INF = 0x3f3f3f3f;

struct Node {
    int x, y, s;
    int cost;
    bool operator<(const Node& other) const {
        return cost > other.cost; // 小顶堆
    }
};

int board[MAX_M][MAX_M];
int dist[MAX_M][MAX_M]; // s: 0（未用魔法），1（魔法颜色0），2（魔法颜色1）
int dx[] = {-1, 1, 0, 0};
int dy[] = {0, 0, -1, 1};

int main() {
    int m, n;
    cin >> m >> n;
    memset(board, -1, sizeof(board));
    for (int i = 0; i < n; ++i) {
        int x, y, c;
        cin >> x >> y >> c;
        board[x][y] = c;
    }
    
    memset(dist, 0x3f, sizeof(dist));
    dist = 0;
    priority_queue<Node> pq;
    pq.push({1, 1, 0, 0});
    
    while (!pq.empty()) {
        Node node = pq.top();
        pq.pop();
        int x = node.x, y = node.y, s = node.s, cost = node.cost;
        if (cost > dist[x][y][s]) continue;
        if (x == m && y == m) continue;
        
        for (int i = 0; i < 4; ++i) {
            int nx

/**************************************************************
	Problem: 1483
	User: caijiajie
	Language: C++
	Result: Compile Error
****************************************************************/