#include <stdio.h>

static int solve(FILE *in, FILE *out);

int main()
{
#ifdef	TARGET_RT_MAC_CFM
	/* For Classic Mac OS users... */
	FILE	*in = fopen("input", "r"), *out = fopen("output", "w");
#else
	FILE	*in = stdin, *out = stdout;
#endif
	while (solve(in, out))
		;
	fclose(in);
	fclose(out);
	return 0;
}

static int solve(FILE *in, FILE *out)
{
	int	numMembers, quorum, date, numDates, index;
	int	numAttendableMembers[100] = { 0 };
	
	fscanf(in, "%d %d", &numMembers, &quorum);
	if (numMembers == 0 && quorum == 0)
		return 0;
	while (numMembers-- > 0) {
		fscanf(in, "%d", &numDates);
		while (numDates-- > 0) {
			fscanf(in, "%d", &date);
			numAttendableMembers[date - 1]++;
		}
	}
	
	numMembers = 0, date = 0;
	for (index = 0; index < 100; index++) {
		if (numAttendableMembers[index] > numMembers) {
			numMembers = numAttendableMembers[index];
			date = index + 1;
		}
	}
	
	if (numMembers < quorum)
		fprintf(out, "0\n");
	else
		fprintf(out, "%d\n", date);
	
	return 1;
}