BOJ_1956.java

import java.io.*;
import java.util.*;

public class BOJ_1956 {

    static final int INF = 987654321;

    public static void main(String[] args) throws Exception {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer(br.readLine());
        int V = Integer.parseInt(st.nextToken());
        int E = Integer.parseInt(st.nextToken());

        int[][] dist = new int[V][V];
        for(int i = 0; i < V; i++) {
            for(int j = 0; j < V; j++) {
                if(i == j) dist[i][j] = 0;
                dist[i][j] = INF;
            }
        }

        for(int i = 0; i<E; i++) {
            st = new StringTokenizer(br.readLine());
            int a = Integer.parseInt(st.nextToken());
            int b = Integer.parseInt(st.nextToken());
            int c = Integer.parseInt(st.nextToken());

            dist[a-1][b-1] = c;
        }

        for(int k = 0; k < V; k++) {
            for(int i = 0; i < V; i++) {
                if(i == k) continue;
                for(int j = 0; j < V; j++) {
                    if(i == j || k == j) continue;

                    dist[i][j] = Math.min(dist[i][j], dist[i][k]+dist[k][j]);
                }
            }
        }

        int answer = INF;
        for(int i = 0; i < V; i++) {
            for(int j = 0; j < V; j++) {
                if(i == j) continue;

                if(dist[i][j] != INF && dist[j][i] != INF) {
                    int tmp = dist[i][j] + dist[j][i];
                    answer = Math.min(answer, tmp);
                }
            }
        }

        System.out.println(answer == INF ? -1 : answer);
    }
}