#include <iostream>

using namespace std;

int main()
{
	int n, m, x;
	int qt = 0, qq = 0;
	cin >> n >> m >> x;
	int M[12501][2];
	int friends[500];
	int fff[500];
	int fff1[500];
	int fff2[500];
	int fff3[500];
	for (int i = 0; i < m; i++) {
		for (int j = 0; j < 2; j++){
			cin >> M[i][j];
		}
	}
	for (int i = 0; i < m; i++) {
		for (int j = 0; j < 2; j++) {
			if (M[i][j] == x) {
				if (j == 1) {
					friends[qt] = M[i][j - 1];
					qt++;
				}
				else {
					friends[qt] = M[i][j + 1];
					qt++;
				}
			}
		}
	}

	for (int i = 0; i < m; i++) {
		for (int j = 0; j < 2; j++) {
			if (M[i][j] != x) {
				if (j == 1) {
					for (int z = 0; z < qt; z++) {
						if (M[i][j] == friends[z] && M[i][j -1] != x) {
							fff[qq] = M[i][j - 1];
							qq++;
						}

					}
				}
				else if (j == 0) {
					for (int z = 0; z < qt; z++) {
						if (M[i][j] == friends[z] && M[i][j + 1] != x) {
							fff[qq] = M[i][j + 1];
							qq++;
						}

					}
				}
			}
		}
	}
	for (int i = 0; i < 500; i++) {
		fff1[i] = 0;
	}
	int qk = 0;
	for (int i = 0; i < qq; i++) {
		if (!fff1[fff[i]]) {
			fff2[qk] = fff[i];
			qk++;
			fff1[fff[i]] = 1;
		}
	}
	int count = 0;
	for (int i = 0; i < qk; i++) {
		for (int j = 0; j < qt; j++) {
			if (friends[j] == fff2[i]) {
				break;
			}
			else if (j == (qt - 1)) {
				fff3[count] = fff2[i];
				count++;
			}
		}
	}
	cout << count << "\n";
	for (int i = 0; i < count; i++) {
		cout << fff3[i] << " ";
	}
}