#include <iostream>
using namespace std;
int main() {
int v, e;
int degree[3001];
cin >> v >> e;
for(int i = 0; i < e; i++){
int a, b;
cin >> a >> b;
degree[a]++;
degree[b]++;
}
int cnt = 0;
for(int i = 1; i < v; i++){
if(degree[i] % 2 != 0){
cnt++;
}
}
if(cnt == 0 || cnt == 2) cout << "YES" << endl;
else cout << "NO" << endl;
return 0;
}
I2luY2x1ZGUgPGlvc3RyZWFtPgp1c2luZyBuYW1lc3BhY2Ugc3RkOwoKaW50IG1haW4oKSB7CglpbnQgdiwgZTsKCWludCBkZWdyZWVbMzAwMV07CgkKCWNpbiA+PiB2ID4+IGU7Cglmb3IoaW50IGkgPSAwOyBpIDwgZTsgaSsrKXsKCQlpbnQgYSwgYjsKCQljaW4gPj4gYSA+PiBiOwoJCWRlZ3JlZVthXSsrOwoJCWRlZ3JlZVtiXSsrOwoJfQoJCglpbnQgY250ID0gMDsKCWZvcihpbnQgaSA9IDE7IGkgPCB2OyBpKyspewoJCWlmKGRlZ3JlZVtpXSAlIDIgIT0gMCl7CgkJCWNudCsrOwoJCX0KCX0KCWlmKGNudCA9PSAwIHx8IGNudCA9PSAyKSBjb3V0IDw8ICJZRVMiIDw8IGVuZGw7CgllbHNlIGNvdXQgPDwgIk5PIiA8PCBlbmRsOwoJcmV0dXJuIDA7Cn0=