#include <stdio.h>
#include <math.h>

struct node {
	double val;
	struct node *next;
};

int main()
{
	struct node *list = NULL, *curr = NULL;
	int read = 1, len = 0;
	double std=0, mean =0;
	char buf[256];

	while (read == 1)
	{
		curr = malloc( 1*sizeof(struct node) );
		fgets(buf,255,stdin);
		if (feof(stdin))
			read = -222;
		else
			read = sscanf(buf,"%lf",&(curr->val));
		if (read == 1)
		{
			len++;
			mean += curr->val;
			if (list == NULL)
			{
				list = curr;
				curr->next = NULL;
			}
			else
			{
				curr->next = list;
				list = curr;
			}
		}
		else
			free(curr);
	}

	mean /= len;
	printf("Mean: %lf\n",mean);

	for (curr = list; curr != NULL; curr = curr->next)
		std += (curr->val - mean)*(curr->val - mean);

	std = sqrt( std / len );
	printf("STD: %lf\n",std);
	
	return 0;
}