#include <cassert>
#include <cstdio>
#include <unordered_set>
#include <list>
#include <iterator>

#define MAXN 100000
#define MAMM 500000

#define ERASE(de, la) do { \
	muchii[de].erase(muchii[de].find(la)); \
	muchii[la].erase(muchii[la].find(de)); \
} while (false);


std::unordered_multiset<int> muchii[MAXN];
std::list<int> ret;

inline void
heir (std::list<int>::iterator ins, int vertex) {
	//fprintf(stderr, "Starting a cicle from %d\n", vertex + 1);

	int i = vertex;
	do {
		int de = i;
		i = *muchii[de].begin();

		//fprintf(stderr, "Deleting the edge between %d and %d\n", de + 1, i + 1);
		ERASE(de, i);
		ret.emplace(ins, i);
		//fprintf(stderr, "Adding %d to tour\n", i + 1);
	} while (i != vertex);
}

#define BUFLEN 100000

class {
	char buf[BUFLEN + 1];
	size_t i = BUFLEN;

	char
	gc () {
		if (i == BUFLEN) {
			buf[fread_unlocked(buf, 1, BUFLEN, stdin)] = '\n';
			i = 0;
		}
		return buf[i ++];
	}

public:
	int
	ParseInt () {
		int ret = 0;
		char c;
		while ((c = gc()) != ' ' && c != '\n')
			ret = (ret << 3) + (ret << 1) + (c & 15);
		return ret;
	}
} input;


int main () {
	int n, m;
	int i;

	freopen("ciclueuler.in",  "r",  stdin);
	freopen("ciclueuler.out", "w", stdout);

	n = input.ParseInt();
	m = input.ParseInt();

	{
		int de, la;
		de = input.ParseInt();
		la = input.ParseInt();
		-- de, -- la;

		ret.emplace_front(de);

		muchii[de].emplace(la);
		muchii[la].emplace(de);
	}

	for (i = 1; i != m; ++ i) {
		int de, la;
		de = input.ParseInt();
		la = input.ParseInt();
		-- de, -- la;

		muchii[de].emplace(la);
		muchii[la].emplace(de);
	}

	for (i = 0; i != n; ++ i) {
		if (muchii[i].size() % 2) {
			puts("-1");
			return 0;
		}
	}


	for (auto it = ret.begin(); it != ret.end();) {
		if (muchii[*it].size())
			heir(std::next(it), *it);
		if (muchii[*it].size() == 0)
			++ it;
	}

	ret.pop_back();

	if (ret.size() == m) {
		for (auto i : ret)
			printf("%d ", i + 1);
	} else {
		puts("-1");
	}
	return 0;
}