#include <bits/stdc++.h>

using namespace std;

const int MAXN = (int) 1e5 + 10;

vector<int> g[MAXN], graph[MAXN], undirectedGraph[MAXN];
int indeg[MAXN], outdeg[MAXN], visited[MAXN];

int n, m;
vector<pair<int, int> > edges;

//set<int> neighbours[MAXN];


void dfs(int from) {
	visited[from] = true;
	for (int to: undirectedGraph[from]) {
		if (!visited[to]) {
			dfs(to);
		}
	}
}

int eulerTourExists() {
	for (int i = 0; i < n; i++) {
		indeg[i] = 0;
		outdeg[i] = 0;
		visited[i] = 0;
		undirectedGraph[i].clear();
	}
	set<pair<int, int> > edgeSet;
	for (int from = 0; from < n; from++) {
		for (auto to: graph[from]) {
			indeg[to]++;
			outdeg[from]++;
			edgeSet.insert(make_pair(from, to));
			edgeSet.insert(make_pair(to, from));	
		}
	}
	/*
	for (int i = 0; i < n; i++) {
		cerr << indeg[i] << " " << outdeg[i] << endl;
	}
	*/
	for (int i = 0; i < n; i++) {
		if (indeg[i] != outdeg[i]) {
			return false;
		}
	}
	for (auto it: edgeSet) {
		undirectedGraph[it.first].push_back(it.second);
	}
	dfs(0);
	for (int i = 0; i < n; i++) {
		if (!visited[i]) {
			return false;
		}
	}
	return true;
}

void sovleSubtask1() {
	for (int mask = 0; mask < (1 << m); mask++) {
		for (int i = 0; i < n; i++) {
			graph[i].clear();	
		}
		for (int i = 0; i < m; i++) {
			int from = edges[i].first, to = edges[i].second;
			if (mask & (1 << i)) {
				// don't change.
				graph[from].push_back(to);
			} else {
				graph[to].push_back(from);
			}
		}
		if (eulerTourExists()) {
			printf("YES\n");
			for (int i = 0; i < m; i++) {
				int from = edges[i].first, to = edges[i].second;
				if (mask & (1 << i)) {
					printf("%d %d\n", from + 1, to + 1);
				} else {
					printf("%d %d\n", to + 1, from + 1);					
				}
			}
			return;
		}
	}
	printf("NO\n");
}

int main() {
	scanf("%d %d", &n, &m);
	assert(n >= 1 && n <= 100000);
	assert(m >= 1 && m <= 100000);
	set<pair<int, int> > st;
	for (int i = 0; i < m; i++) {
		int from, to;
		scanf("%d %d", &from, &to);
		assert(from >= 1 && from <= n);
		assert(to >= 1 && to <= n);
		assert(from != to);
		st.insert(make_pair(from, to));
		from--;
		to--;
		g[from].push_back(to);
		edges.push_back(make_pair(from, to));
	}
	assert(st.size() == m);

	sovleSubtask1();
	
	return 0;
}