/*
 * Program to read grades (numbers between 0 and 100 inclusive) input 
 * and report how many fall into ranges 0 .. 9, 10 .. 19, etc.
 *
 * Input:  Zero or more integers, read from standard input, terminated 
 * by anything other than a number. 
 *
 * Output:  Error messages for any input numbers that are "out of range" 
 *   (not between 0 and 100), then counts of how many input numbers are
 *   in each of the following ranges:
 *
 *    0 <= n < 9
 *   10 <= n < 19
 *   ....
 *   90 <= n < 100
 */
#include <stdio.h>

int main(void) {

	int input;

	int counts[10] = { 0 };

	int index;

	int low, high;

	printf("enter grades (between 0 and 100), non-number to end:\n");

		while (scanf("%d", &input) == 1) {
			/* if input is not in 0 .. 100 range, print error message */
			if ((input < 0) || (input > 100)) {
				printf("grades must be between 0 and 100\n");
			}
			/* figure out which counter to update and update it */
			else {
				if (input == 100)
					index = 9;
				else
					index = input / 10;
				counts[index] += 1;
			}
		}

	/* print counts */
	for (index = 0; index <= 9; ++index) {
		/* compute start and end of each grade range */
		low = index * 10;
		if (index == 9) {
			high = 100;
		}
		else {
			high = low + 9;
		}
		printf("%d grades between %d and %d\n", counts[index], 
				low, high);
	}

	return 0;
}