#include <stdio.h>

#define NUMBER_OF_STUDENTS 10

void average()
{
float score = 0, sum = 0;
int i;

for(i = 0 ; i < NUMBER_OF_STUDENTS ; i++)
{
scanf("%f", &score);
sum = sum + score;
}

printf("%.7f\n", sum / NUMBER_OF_STUDENTS);
}

int main()
{
average();
}