#include <stdio.h>

int sum = 0;
int count = 0;

double avgup(int n) {
	sum += n;
	count++;
	
	return (double)sum / count;
}

int main(void) {
	int x;
	double average;
	
	while(1) {
		scanf("%d",&x);
		
		if(x < 0) {
			break;
		}
		
		average = avgup(x);
		printf("%.1f\n", average);
	}
	

	return 0;
}