#include <bits/stdc++.h>
using namespace std;
int n,m;
bool check=false;
vector <int> g[100001];
int color[100001];
bool dfs(int u) {
    if (color[u] == 1)
        return true;
    if (color[u] == 2)
        return false;
    color[u] = 1;
    for (auto v : g[u]) {
        if (dfs(v))
            return true;
    }
    color[u] = 2;
    return false;
}

int main(){

    scanf("%d %d",&n,&m);
    for(int i=1;i<=m;i++){
        int u,v;
        scanf("%d %d",&u,&v);
        g[u].push_back(v);
    }
    for(int i=1;i<=n;i++){
        for(auto v:g[i]){
            if(dfs(v)){
                check=true;
                break;
            }
        }
    }
    if(check) printf("Yes");
    else printf("No");

    return 0;
}