#include<stdio.h>

int main(void){
    int N,M;
    int sa[124750],sb[124750];
    int count[501]={0};
    int Count=0;

    scanf("%d", &N);
    scanf("%d", &M);

    for(int i=0;i<M;i++){
        scanf("%d", &sa[i]);
        scanf("%d", &sb[i]);

        count[sa[i]]++;
        count[sb[i]]++;
    }

    for(int j=0;j<=N-1;j++){
        if(count[j]%2==1){
            Count++;
        }
    }

    if(Count>2) printf("NO\n");

    else printf("YES\n");

    return 0;

}