#include <stdio.h>
#include <stdlib.h>
#include <malloc.h>

int main()
{
	int i, t, l, sum;
    int *PIN;
	
	/* read array's size*/
	scanf("%d", &t);
		
	/* allocate memory */
	PIN = (int *) malloc(t * sizeof(int));
	if (!PIN) {
	   fprintf(stderr, "Out of memory\n");
	   exit(1);
	}

    /* read values */
	for(l=0; l<t; l++)	{
		scanf("%d", &PIN[l]);
	}
	
	/* sum values */
    sum = 0;
	for(i=1; i<t; i++)	{
		sum += PIN[i];
	}
	
	/* print the mean average */
	printf("%f\n", (float)sum/t);
	
	
	/* free the memory */
	free(PIN);
	return 0;
}