tioj 1209

using namespace std;
#include <iostream>
#include <vector>
#define pb push_back
#include <bitset>
#include <utility>
#define pii pair<int,int>

vector <int> graph[40040];
int depth[40040];
bitset <40040> visited;
pii edge[500500];

void Init(int n){
    visited.reset();
    for (int i=0;i<=n;++i){
        graph[i].clear();
    }
}

void dfs(int x,int dep){
    visited[x] = true;
    depth[x] = dep;

    for (auto i:graph[x]){
        if (visited[i]){
            continue;
        }
        dfs(i,dep+1);
    }
}

int main(){
    ios_base::sync_with_stdio(false),cin.tie(0);
    int n,m;

    while (cin >> n >> m && (n || m)){
        Init(n);

        for (int i=0;i<m;++i){
            int st,ed;
            cin >> st >> ed;

            graph[st].pb(ed);
            graph[ed].pb(st);
            edge[i] = {st,ed};
        }

        for (int i=1;i<=n;++i){
            if (!visited[i])
                dfs(i,0);
        }

        //for (int i=1;i<=n;++i)cout << depth[i] << ' '; cout << '\n';

        bool isBipartite = true;
        for (int i=0;i<m;++i){
            if (depth[edge[i].first] % 2 == depth[edge[i].second] % 2){
                isBipartite = false;
                break;
            }
        }

        cout << (isBipartite ? "Yes\n" : "No\n");
    }

    return 0;
}