#include <stdio.h>
#include <stdlib.h>
#include <string.h>
/*int main()
{
int n,MF[2] = {0,0};
char a[150][100], *p;
scanf("%d", &n);
for(int i=0; i<n; i++)
{
scanf("%s", a[i]);
}
for(int i=0; i<n; i++)
{
p = strchr(a[i], ',');
if(strncmp(p+1, "M",1)==0)
{
MF[0]++;
}
else
{
MF[1]++;
}
}
printf("%d\n%d", MF[0], MF[1]);
}*/
typedef struct person
{
char n;
char g;
int a;
} person;
int main()
{
int n,sum=0;
char s[150][100]={}, *p;
scanf("%d", &n);
person *list = malloc(sizeof(person) * n);
for(int i=0; i<n; i++)
{
scanf("%s", s[i]);
}
for(int i=0; i<n; i++)
{
p = strtok(s[i], ",");
strcpy(list[i].n, p);
p = strtok(s[i],",");
strcpy(list[i].g, p);
p = strtok(s[i],",");
list[i].a = atoi(p);
sum+=list[i].a;
}
free(list);
printf("%.2f",(double)sum/n);
}