#pragma comment(linker, "/STACK:1024000000,1024000000")
#include<iostream>
#include<cstdio>
#include<cstring>
#include<string>
#include<cmath>
#include<cstdlib>
#include<algorithm>
#include<vector>
using namespace std;
struct node
{
    int v,w;
    node(int _v, int _w) : v(_v), w(_w) {}
};
vector<node> e[100001];
int n,m,fa[100001],dp[100001],ans;
int find(int x)
{
    if(x!=fa[x])
        fa[x]=find(fa[x]);
    return fa[x];
}
void dfs(int u,int father)
{
    int maxx=0;
    for(int i=0;i<e[u].size();i++)
    {
        int v=e[u][i].v;
        int w=e[u][i].w;
        if(v==father)
            continue;
        dfs(v,u);
        ans=max(ans,dp[v]+maxx+w);
        maxx=max(maxx,dp[v]+w);
    }
    dp[u]=maxx;
}
void slove()
{
    for(int i=1;i<=n;i++)
    {
        if(dp[i]==-1)
            dfs(i,-1);
    }
    printf("%d\n",ans);
}
int main()
{
    while(scanf("%d%d",&n,&m)!=EOF)
    {
        bool flag=false;
        ans=0;
        for(int i=1;i<=n;i++)
            fa[i]=i,dp[i]=-1,e[i].clear();
        for(int i=1;i<=m;i++)
        {
            int x,y,z;
            scanf("%d%d%d",&x,&y,&z);
            e[x].push_back(node(y,z));
            e[y].push_back(node(x,z));
            if(flag)
                continue;
            int fx,fy;
            fx=find(x),fy=find(y);
            if(fx!=fy)
            {
                fa[fx]=fy;
            }
            else
            {
                flag=true;
                continue;
            }
        }
        if(flag)
        {
            printf("YES\n");
            continue;
        }
        slove();
    }
    return 0;
}