#include <bits/stdc++.h>
using namespace std;

const int N = 2005, M = 10005;

int head[N], cnt;
int n, m;
int dis[N], backup[N];
int in[N];  //记录节点入队多少次
bool st[N];

struct
{
   
    int u, v, w;
    int nxt;
} edges[M];

int spfa(int src, int des)
{
   
    memset(dis, 0x3f, sizeof dis);
    memset(st, 0, sizeof st);
    memset(in, 0, sizeof in);
    queue<int> q;

    dis[src] = 0;
    q.push(src);
    st[src] = true;
    in[src]++;

    while (!q.empty())
    {
   
        int f = q.front();
        q.pop();
        st[f] = false;

        for(int e = head[f]; e != 0; e = edges[e].nxt) {
   
            int u = edges[e].u, v = edges[e].v, w = edges[e].w;

            if (dis[v] > dis[u] + w) {
   
                dis[v] = dis[u] + w;
                if (in[v] > n)
                    return 0;   //若不存在负环，一个点最多可以入队n次
                if (!st[v]) {
   
                    q.push(v);
                    st[v] = true;
                    in[v]++;
                }
            }
        }
    }

    if (dis[des] < 0x3f3f3f) {
   
        return dis[des];
    }
    else {
   
        return -1;
    }
}

int main()
{
   
#ifndef ONLINE_JUDGE
    freopen("D:/VS CODE/C++/in.txt", "r", stdin);
    freopen("D:/VS CODE/C++/out.txt", "w", stdout);
#endif
    cin >> n >> m;

    for (int i = 0; i < m; ++i)
    {
   
        int u, v, w;
        scanf("%d %d %d", &u, &v, &w);
        edges[++cnt].nxt = head[u];
        edges[cnt].u = u;
        edges[cnt].v = v;
        edges[cnt].w = w;
        head[u] = cnt;
    }

    int d1 = spfa(1, n);
    int d2 = spfa(n, 1);

    if (d1 == 0 or d2 == 0) {
   
        printf("Yes");
    }
    else {
   
        printf("No");
    }

    fclose(stdin);
    fclose(stdout);
    return 0;
}