rt.

#include<bits/stdc++.h>
using namespace std;
int cnt=0;
struct node{
  int a,b;
}e[200005];
int sum[200005];
int main(){
  int n,m;
  cin>>n>>m;
  if((n-m)!=1){cout<<"No";return 0;}
  for(int i=0;i<m;i++){
    cin>>e[i].a>>e[i].b;
    sum[e[i].a]++;sum[e[i].b]++;
  }
  for(int i=0;i<n;i++){
    if(sum[i]>2||sum[i]==0){cout<<"No";return 0;}
    else if(sum[i]==1)cnt++;
    if(cnt>2){cout<<"No";return 0;}
  }
  cout<<"Yes";
}