#include <stdio.h>
#include <iostream>
#include <algorithm>
#include <cstdlib>
#include <sstream>
#include <numeric>
#include <cstring>
#include <bitset>
#include <string>
#include <deque>
#include <stack>
#include <cmath>
#include <queue>
#include <set>
#include <map>
using namespace std;
#define INF 0x3f3f3f3f
#define LC(x) (x<<1)
#define RC(x) ((x<<1)+1)
#define MID(x,y) ((x+y)>>1)
#define CLR(arr,val) memset(arr,val,sizeof(arr))
#define FAST_IO ios::sync_with_stdio(false);cin.tie(0);
typedef pair<int, int> pii;
typedef long long LL;
const double PI = acos(-1.0);
const int N = 100010;
const int M = 1000010;
struct edge
{
    int to, nxt, dx;
    edge() {}
    edge(int To, int Nxt, int Dx): to(To), nxt(Nxt), dx(Dx) {}
};
edge E[M << 1];
int head[N], tot;
int dp[N][2];
int pre[N];
bitset<N>vis;

void init()
{
    CLR(head, -1);
    tot = 0;
    CLR(dp, 0);
    CLR(pre, -1);
    vis.reset();
}
int Find(int n)
{
    if (pre[n] == -1)
        return n;
    return  pre[n] = Find(pre[n]);
}
bool joint(int a, int b)
{
    a = Find(a), b = Find(b);
    if (a == b)
        return false;
    pre[a] = b;
    return true;
}
inline void add(int s, int t, int d)
{
    E[tot] = edge(t, head[s], d);
    head[s] = tot++;
}
void dfs(const int &u, const int &pre)
{
    vis[u] = true;
    for (int i = head[u]; ~i; i = E[i].nxt)
    {
        int v = E[i].to;
        if (v != pre)
        {
            dfs(v, u);
            int temp = dp[v][0] + E[i].dx;
            if (temp > dp[u][0])
            {
                dp[u][1] = dp[u][0];
                dp[u][0] = temp;
            }
            else if (temp > dp[u][1])
                dp[u][1] = temp;
        }
    }
}
int main(void)
{
    int n, m, a, b, c, i;
    while (~scanf("%d%d", &n, &m))
    {
        init();
        bool ok = true;
        for (i = 0; i < m; ++i)
        {
            scanf("%d%d%d", &a, &b, &c);
            add(a, b, c);
            add(b, a, c);
            if (!joint(a, b))
                ok = false;
        }
        if (!ok)
            puts("YES");
        else
        {
            for (i = 1; i <= n; ++i)
                if (!vis[i])
                    dfs(i, -1);
            int ans = -INF;
            for (i = 1; i <= n; ++i)
                if (dp[i][0] + dp[i][1] > ans)
                    ans = dp[i][0] + dp[i][1];
            printf("%d\n", ans);
        }
    }
    return 0;
}