#include <stdio.h>

#define SPACES 4
#define SLIMIT 1000

int getlinec(char line[], int lim);
void spacetotab(char result[], char line[]);
/*
Replaces strings of blanks by the minimum number of tabs and blanks
*/
int main()
{
	char line[SLIMIT];
	char result[SLIMIT];
	while (getlinec(line, SLIMIT) > 0) {
		spacetotab(result, line);
		printf("%s\n", result);
	}

	return 0;
}

/*
gets input from stdin and stores it in a string (null-terminated and '\n'ed)
*/
int getlinec(char line[], int lim)
{
	int i, c;

	for(i = 0; i < lim - 1 && (c = getchar()) != EOF && c != '\n'; i++)
		line[i] = c;
	if(line[i] == '\n') {
		line[i] = '\n';
		i++;
	}
	line[i] = '\0';

	return i;
}

/*
turns each four spaces to a tab in a string(not '\n'ed)
*/
void spacetotab(char result[], char line[])
{
	int i, j;
	int spaces = 0; // count spaces

	i = j = 0;
	while (line[i] != '\0') {
		if(line[i] == ' ') {
			spaces++;
			i++;
		} else {
			result[j] = line[i];
			i++;
			j++;
		}
		if(spaces == 4) {
			result[j] = '\t';
			spaces = 0;
			j++;
		}
	}
	result[j] = '\0'; // null terminate
}