import java.io.IOException;
import java.io.InputStream;
import java.util.*;

public class Main {

    public static void main(String[] args) {
        FastScanner sc = new FastScanner();
        int n = sc.nextInt();
        WGraph g = new WGraph(n);
 
        for(int i=0;i<n-1;i++){
            g.addEdge(sc.nextInt(), sc.nextInt(), sc.nextInt());
        }
         
        System.out.println(g.treeDiameter());
    }
	
}

class WGraph {
	WEdgeList[] elist;
	
	public WGraph(int vnum){
		this.elist = new WEdgeList[vnum];
		for(int i=0;i<vnum;i++){
			elist[i] = new WEdgeList();
		}
	}

	//同じ辺を複数回追加すると多重辺が生まれてしまう
	public void addEdge(int a, int b, int w){
		elist[a].add(new WEdge(b,w));
		elist[b].add(new WEdge(a,w));
	}
	
	//頂点数を返す
	public int vnum(){
		return elist.length;
	}
	
	//辺数を返す
	public int edgeNum(){
		int sum = 0;
		for(WEdgeList l:elist){
			sum += l.size();
		}
		return sum/2;
	}
	
	//隣接判定
	public boolean isNext(int n, int m){
		return elist[n].contains(m);
	}
	
	//隣接する全ての頂点を返す
	public ArrayList<Integer> nextList(int n){
		ArrayList<Integer> l = new ArrayList<>();
		for(WEdge e:elist[n]){
			l.add(e.to);
		}
		return l;
	}
	
	//隣接する全ての辺を返す
	public WEdgeList EList(int n){
		return elist[n];
	}
	
	//ダイクストラ法でsからの最短距離列を求める。到達不可はMAXVALUE。
	public int Dijkstra(int start, int goal){
		
		PriorityQueue<NextNode> frontier = new PriorityQueue<>((x,y)->Integer.compare(x.g, y.g));
		boolean[] isExplored = new boolean[vnum()];
		int[] g = new int[vnum()];
		Arrays.fill(g, Integer.MAX_VALUE);
		
		g[start] = 0;
		frontier.add(new NextNode(start,0));
		
		while(!frontier.isEmpty()){
			NextNode now = frontier.poll();
			if(now.i == goal){
				return g[now.i];
			}
			
			if(!isExplored[now.i]){
				isExplored[now.i] = true;
				
				for(WEdge e:EList(now.i)){
					if(isExplored[e.to]){
						continue;
					}
					
					int next = e.to;
					if(g[next] <= g[now.i] + e.w){
						continue;
					}
					
					g[next] = now.g + e.w;
					frontier.add(new NextNode(next,g[next]));
				}	
			}
		}
		
		return -1;
	}
	//ダイクストラ法でsからの最短距離列を求める。到達不可はMAXVALUE。
	public int[] DijkstraArray(int start){
		
		PriorityQueue<NextNode> frontier = new PriorityQueue<>((x,y)->Integer.compare(x.g, y.g));
		boolean[] isExplored = new boolean[vnum()];
		int[] g = new int[vnum()];
		Arrays.fill(g, Integer.MAX_VALUE);
		
		g[start] = 0;
		frontier.add(new NextNode(start,0));
		
		while(!frontier.isEmpty()){
			NextNode now = frontier.poll();
			
			if(!isExplored[now.i]){
				isExplored[now.i] = true;
				
				for(WEdge e:EList(now.i)){
					if(isExplored[e.to]){
						continue;
					}
					
					int next = e.to;
					if(g[next] <= g[now.i] + e.w){
						continue;
					}
					
					g[next] = now.g + e.w;
					frontier.add(new NextNode(next,g[next]));
				}	
			}
		}
		
		return g;
	}
	class NextNode{
		int i;
		int g;
		public NextNode(int i, int g){
			this.i=i;
			this.g=g;
		}
	}
	
	//全点対最短距離をワーシャルフロイド法で求める
	public int[][] WarshallFloyd(){
		int[][][] d = new int[vnum()+1][vnum()][vnum()];
		
		for(int k=0;k<vnum()+1;k++){
			for(int i=0;i<vnum();i++){
				Arrays.fill(d[k][i], Integer.MAX_VALUE);
				d[k][i][i] = 0;
			}
		}

		for(int i=0;i<vnum();i++){
			for(WEdge e:elist[i]){
				d[0][i][e.to] = e.w;
			}
		}
		
		for(int k=1;k<vnum()+1;k++){
			for(int i=0;i<vnum();i++){
				for(int j=0;j<vnum();j++){
					if((d[k-1][i][k-1] != Integer.MAX_VALUE) && (d[k-1][k-1][j] != Integer.MAX_VALUE)){
						d[k][i][j] = Math.min(d[k-1][i][j], d[k-1][i][k-1] + d[k-1][k-1][j]);
					}
					else{
						d[k][i][j] = d[k-1][i][j];
					}
				}
			}
		}
		
		return d[vnum()];
	}
	
	//木であることを仮定して直径を求める
	public int treeDiameter(){
		int[] d1 = DijkstraArray(0);
		int s = maxIndex(d1);
		int[] d2 = DijkstraArray(s);
		return max(d2);
	}
	//配列の最大値
	static int max(int[] a){
		int max = Integer.MIN_VALUE;
		for(int i:a){
			if(i>max){
				max = i;
			}
		}
		return max;
	}
	//配列の最大値のインデックス
	static int maxIndex(int[] a){
		int max = Integer.MIN_VALUE;
		int idx = 0;
		for(int i=0;i<a.length;i++){
			if(a[i]>max){
				max = a[i];
				idx = i;
			}
		}
		return idx;
	}
	
	
	class WEdgeList extends ArrayList<WEdge>{
		private static final long serialVersionUID = 4901656039324433445L;
	}
	class WEdge{
		int to;
		int w;
		
		public WEdge(int to, int w){
			this.to = to;
			this.w = w;
		}
	}
}

class FastScanner {
	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() {
		if (hasNextByte())
			return buffer[ptr++];
		else
			return -1;
	}
	private static boolean isPrintableChar(int c) {
		return 33 <= c && c <= 126;
	}
	public boolean hasNext() {
		while (hasNextByte() && !isPrintableChar(buffer[ptr]))
			ptr++;
		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 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();
		}
	}
	public int nextInt() {
		long nl = nextLong();
		if (nl < Integer.MIN_VALUE || nl > Integer.MAX_VALUE)
			throw new NumberFormatException();
		return (int) nl;
	}
	public double nextDouble() {
		return Double.parseDouble(next());
	}
}


Measured memory_bytes: 58724