#include <stdio.h>

#define MAX 100

int flags[MAX] = {0};

int urand(void)
{
	int k, val;

	for (k=0;k<MAX;++k)
		if (flags[k] == 0)
			break;
	if (k == MAX)
		return -1;

	while (flags[val = rand() % MAX])
		;
	++flags[val];

	return val;
}

int main()
{
	int k;

	srand(time(0));

	for (k = 0; k < MAX; ++k)
		printf("%d ", urand());

	printf("\n\n%d\n", urand());

	return 0;
}