package graph;

import java.io.*;

import java.util.StringTokenizer;
import java.util.Arrays;

public class Kruskall implements Runnable {

	class Edge implements Comparable<Edge> {
		int v1;
		int v2;
		int weight;

		Edge(int v1, int v2, int weight) {
			this.v1 = v1;
			this.v2 = v2;
			this.weight = weight;
		}

		public int compareTo(Edge that) {
			if(weight < that.weight) return -1;
			if(weight > that.weight) return 1;
			return 0;
		}
	}

	class DSU {
		int[] p;
		int[] r;

		DSU(int n) {
			p = new int[n];
			r = new int[n];

			for(int i = 0; i < n; i++) p[i] = i;
		}

		int get(int i) {
			if(i != p[i]) {
				p[i] = get(p[i]);
			}
			return p[i];
		}

		void union(int i, int j) {
			i = get(i);
			j = get(j);

			if(r[i] == r[j]) r[i]++;

			if(r[i] < r[j]) p[i] = j;
			else p[j] = i;
		}
	}

	int n;
	int m;

	Edge[] edges;

	DSU trees;

	public void run() {
		try {
			BufferedReader in = new BufferedReader(new FileReader("mindiff.in"));
			PrintWriter out = new PrintWriter("mindiff.out");
			StringTokenizer st = new StringTokenizer(in.readLine());

			n = Integer.parseInt(st.nextToken());
			m = Integer.parseInt(st.nextToken());

			if(n == 1) {
				out.println("YES");
				out.print(0);
				out.close();
			}

			edges = new Edge[m];
			trees = new DSU(n + 1);

			int t1;
			int t2;
			int t3;

			for(int i = 0; i < m; i++) {
				st = new StringTokenizer(in.readLine());

				t1 = Integer.parseInt(st.nextToken());
				t2 = Integer.parseInt(st.nextToken());
				t3 = Integer.parseInt(st.nextToken());

				edges[i] = new Edge(t1, t2, t3);
			}

			Arrays.sort(edges);

			Edge e;

			Edge min;
			Edge max;

			double res = Double.POSITIVE_INFINITY;

			for(int j = 0; j < m; j++) {

				min = edges[j];
				max = edges[j];

				trees = new DSU(n + 1);

				for (int i = 0; i < m; i++) {
					e = edges[i];

					if(e.weight < min.weight) continue;

					if (trees.get(e.v1) != trees.get(e.v2)) {

						if(max.weight < e.weight) max = e;

						trees.union(e.v1, e.v2);
					}
				}

				boolean good = true;

				for(int i = 0; i < m; i++) {
					e = edges[i];
					if(trees.get(e.v1) != trees.get(e.v2)) {
						good = false;
						break;
					}
				}

				if(good) res = Math.min(res, max.weight - min.weight);

			}

			out.println("YES");

			out.print((int)res);

			in.close();
			out.close();
		} catch(Exception e) {
			e.printStackTrace();
		}
	}

	public static void main(String[] args) {
		new Thread(new Kruskall()).start();
	}
}