import java.io.IOException;
import java.io.InputStream;
import java.util.NoSuchElementException;
import java.util.Arrays;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Comparator;
import java.util.Queue;
import java.util.PriorityQueue;

public class Main {
	public static class Node { 
		int n;
		int cost;
		public Node(int n) {
			this.n = n;
			this.cost = Integer.MAX_VALUE;
		}
	}

	public static class NodeComparator implements Comparator {
		public int compare(Object o1, Object o2) {
			Node n1 = (Node)o1;
			Node n2 = (Node)o2;
			if(n1.cost > n2.cost) return 1;
			if(n1.cost < n2.cost) return -1;
			return 0;
		}
	}

	public static Comparator<Node> nodeComparator = new Comparator<Node>() {
		@Override
		public int compare(Node n1, Node n2) {
			return n1.cost-n2.cost;
		}
	};

	public static int[] dijkstraImprove(int n, int start, ArrayList<HashMap<Integer, Integer>> matrix) {
		int[] cost = new int[n];
		boolean[] isChecked = new boolean[n];
		Node[] nodes = new Node[n];
		for(int i=0; i<n; i++) {
			nodes[i] = new Node(i);
		}

		Queue<Node> q = new PriorityQueue<Node>(1, nodeComparator);
		nodes[start].cost = 0;
		q.add(nodes[start]);
		while(!q.isEmpty()) {
			Node node = q.poll();
			if(isChecked[node.n]) continue;
			isChecked[node.n] = true;
			HashMap<Integer, Integer> vector = matrix.get(node.n);
			for(int key: vector.keySet()) {
				if(isChecked[key]) continue;
				if(nodes[node.n].cost+vector.get(key) < nodes[key].cost) {
					nodes[key].cost = nodes[node.n].cost+vector.get(key);
					q.add(nodes[key]);
				}
			}
		}
		for(int i=0; i<n; i++) {
			cost[i] = nodes[i].cost;
		}
		return cost;
	}

	public static int[] dijkstra(int n, int start, ArrayList<HashMap<Integer, Integer>> matrix) {
		boolean[] defnode = new boolean[n];
		int[] cost = new int[n];
		for(int i=0; i<n; i++) {
			defnode[i] = false;
			cost[i] = Integer.MAX_VALUE;
		}
		cost[start] = 0;
		int node = start;
		int counter = 0;
		while(true) {
			counter++;
			if(counter == n || node == Integer.MAX_VALUE) return cost;
			defnode[node] = true;
			HashMap<Integer, Integer> list = matrix.get(node);
			for(int key: list.keySet()) {
				if(defnode[key]) continue;
				cost[key] = Math.min(cost[key], cost[node]+list.get(key));
			}
			int minnode = Integer.MAX_VALUE;
			int mincost = Integer.MAX_VALUE;
			for(int i=0; i<n; i++) {
				if(defnode[i]) continue;
					if(cost[i] < mincost) {
						minnode = i;
						mincost = cost[i];
					}
				}
			node = minnode;
		}
	}

	public static int maxIndex(int[] lst) {
		int tmpMax = 0;
		int maxIdx = -1;
		for(int i=0; i<lst.length; i++) {
			if(tmpMax <= lst[i]) {
				tmpMax = lst[i];
				maxIdx = i;
			}
		}
		return maxIdx;
	}

	public static void main(String[] args) {
		FS r = new FS();
		int v = r.nextInt();
		ArrayList<HashMap<Integer,Integer>> matrix = new ArrayList<HashMap<Integer,Integer>>();
		for(int i=0; i<v; i++) {
			matrix.add(new HashMap<Integer,Integer>());
		}

		for(int i=0; i<v-1; i++) {
			int s = r.nextInt();
			int t = r.nextInt();
			int d = r.nextInt();
			matrix.get(s).put(t, d);
			matrix.get(t).put(s, d);
		}

		// int[] cost = dijkstra(v, maxIndex(dijkstra(v, 0, matrix)), matrix);
		int[] cost = dijkstraImprove(v, maxIndex(dijkstraImprove(v, 0, matrix)), matrix);
		System.out.println(cost[maxIndex(cost)]);
	}
	
	// Read Class
	static class FS {
		private final InputStream in = System.in;
		private final byte[] buffer = new byte[1024];
		private int ptr = 0;
		private int buflen = 0;
		private boolean hasNextByte() {
			if (ptr < buflen) {
				return true;
			} else {
				ptr = 0;
				try {
					buflen = in.read(buffer);
				} catch (IOException e) {
					e.printStackTrace();
				}
				if (buflen <= 0) {
					return false;
				}
			}
			return true;
		}
	
		private int readByte() { return hasNextByte() ? buffer[ptr++] : -1;}
		private boolean isPrintableChar(int c) {return 33 <= c && c <= 126;}
		private void skipUnprintable() {while(hasNextByte() && !isPrintableChar(buffer[ptr])) ptr++;}
	
		public boolean hasNext() { skipUnprintable(); return hasNextByte();}
		public String next() {
			if (!hasNext()) throw new NoSuchElementException();
			StringBuilder sb = new StringBuilder();
			int b = readByte();
			while(isPrintableChar(b)) {
				sb.appendCodePoint(b);
				b = readByte();
			}
			return sb.toString();
		}
		public int nextInt() {
			return (int)nextLong();
		}
		public long nextLong() {
			if (!hasNext()) throw new NoSuchElementException();
			long n = 0;
			boolean minus = false;
			int b = readByte();
			if (b == '-') {
				minus = true;
				b = readByte();
			}
			if (b < '0' || '9' < b) {
				throw new NumberFormatException();
			}
			while(true) {
				if ('0' <= b && b <= '9') {
					n *= 10;
					n += b - '0';
				} else if(b == -1 || !isPrintableChar(b)) {
					return minus ? -n : n;
				} else {
					throw new NumberFormatException();
				}
				b = readByte();
			}
		}
	}
}

Measured memory_bytes: 94640