#include<stdio.h>
int main(){
    int size;
    int ind;
    float total;
    float average;
    
    int arr[size];
    for(ind=0;ind<size;ind++){
        scanf("%d",&arr[ind]);
    }
      for(ind=0;ind<size;ind++){
          if(arr[i]<0){
            printf("Invalid input");
        return 0;  
          }
      }
      
    for(ind=0;ind<size;ind++){
        total+=arr[ind];
    }
    average=(float)total/size;
    printf("%.2f",average);
    return 0;
}