#define _CRT_SECURE_NO_WARNINGS

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <ctime>

using namespace std;

const char* INPUT_FILE_NAME		= "bits.in";
const char* OUTPUY_FILE_NAME	= "bits.out";

int n, m, k;
char strings[64][64];
bool data[64 * 64];
bool bits[64];

void readInput() {
	FILE* finp = fopen(INPUT_FILE_NAME, "r");
	fscanf(finp, "%d%d", &n, &k);
	for (int i = 0; i < n; ++i)
		fscanf(finp, "%s%d", &strings[i], &bits[i]);
	fclose(finp);
	m = strlen(strings[0]);
	for (int i = 0; i < n; ++i)
		for (int j = 0; j < m; ++j)
			data[i * m + j] = !!(strings[i][j] - '0');
}

void writeInput() {
	printf("%d %d %d\n", n, m, k);
	for (int i = 0; i < n; ++i) {
		for (int j = 0; j < m; ++j)
			printf("%d", data[i * m + j]);
		printf(" %d\n", bits[i]);
	}
}

int elementsCount;
char comb[16];

void printComb() {
	printf("Comb:\n");
	for (int i = 0; i < elementsCount; ++i)
		printf("%d ", comb[i]);
	printf("\n");
}

void writeOutput() {
	FILE* fout = fopen(OUTPUY_FILE_NAME, "w");
	fprintf(fout, "%d\n", elementsCount);
	for (int i = 0; i < elementsCount; ++i)
		fprintf(fout, "%d\n", comb[i]);
	fclose(fout);
}

void checkComb() {
	for (int i = 0; i < n; ++i) {
		bool result = data[i * m + comb[0]];
		for (int j = 1; j < elementsCount; ++j) {
			result ^= data[i * m + comb[j]];
		}
		if (result != bits[i])
			return;
	}
	writeOutput();
	cout << (double)clock() / CLOCKS_PER_SEC << endl;
	exit(0);
}

void genComb(int i, int j) {
	if (i >= elementsCount) return;
	for (int l = j; l < m; ++l) {
		comb[i] = l;
		if (i == elementsCount - 1) {
			//printComb();
			checkComb();
		}
		genComb(i + 1, l + 1);
	}
}

void solve() {
	for (int i = 1; i <= k; ++i) {
		elementsCount = i;
		genComb(0, 0);
	}
}

int main() {
	readInput();
	//writeInput();
	solve();
	writeOutput();

	FILE* fout = fopen(OUTPUY_FILE_NAME, "w");
	fprintf(fout, "-1\n");
	fclose(fout);

	return 0;
}