/*
 * compute sum of integers entered as input (any number of them), using
 * recursion
 */
#include <stdio.h>

/*
 * compute sum of integers from stdin, stopping when anything else
 * is entered
 */
int sum(void) {
	int n;
	if (scanf("%d", &n) == 1) {
		/* add this input to sum of remaining inputs */
		return n + sum();
	}
	else {
		/* non-integer input */
		return 0;
	}
}

/* main */
int main(void) {
	printf("enter integers to sum, anything else to stop\n");
	printf("sum %d\n", sum());
	return 0;
}