#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define ff first
#define ss second
ll ttt;
const ll INF=1e18;
const ll MOD=1e9+7;
const ll N=300007;
ll n,m,k;
vector<ll>g[N];
ll sz[N];
bool used[N];
void dfs(int v, int par=-1){
// cout<<"YOO"<<endl;
sz[v]=0;
for(int to:g[v]){
if(to!=par){
dfs(to,v);
sz[v]=max(sz[v],sz[to]+1);
}
}
}
bool is_tree(int v, int par=-1){
used[v]=true;
for(int to:g[v]){
if(to!=par){
if(used[to])return false;
if(!is_tree(to,v))return false;
}
}
return true;
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
// freopen("output.txt","w",stdout);
// freopen("input.txt","r",stdin);
cin>>n>>m;
// if(m!=n-1)cout<<"NO\n";
for(int i=0;i<m;i++){
int x,y;
cin>>x>>y;
g[x].push_back(y);
g[y].push_back(x);
}
for(int v=1;v<=n;v++){
if(!used[v]&&!is_tree(v)){
cout<<"NO\n";
return 0;
}
}
for(int v=1;v<=n;v++){
dfs(v);
int cnt=0;
for(int to:g[v]){
cnt+=(sz[to]>2);
}
if(cnt>2){
cout<<"NOss\n";
return 0;
}
}
cout<<"YES 1 1\n";
}
