#include <stdio.h>

int main()
{
	int sum = 0;
	int count = 0;
	int number;

	scanf("%d", &number);
	while ( number != -1 ) {
		sum += number;
		count ++;
		scanf("%d", &number);
	}

	double dsum = sum;
	printf("The average is %f.\n", dsum / count);

	return 0;
}