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

int validate_and_parse(const char*token,int*score){
    long val;
    char*endptr;
    if(token == NULL||*token=='\0'){
        return 0;
    }
if(strchr(token,'.')!=NULL){
    return 0;

}
   val = strtol(token,&endptr,10);
   if(*endptr != '\0' && *endptr != '\n' && *endptr != '\r') return 0;
   if (val< 0 ) return 0;
   if(val>100) return 0;
   *score = (int)val;
   return 0;
 }
int main() {
    int N;
    long long sum = 0;
    int is_invaild = 0;
    int score_count= 0;
    char line_buffer[4096];
    
    if (fgets(line_buffer,sizeof(line_buffer), stdin)== NULL {
        is_invalid = 1;
    } else if (sscanf(line_buffer, "%d", &N) !=1 {
        is_invalid=1;
    }
     if (!is_invalid && (N < 1|| N>100)){
         is_valid = 1;
         
     }
     if ( !is_invalid){
         if(fgets(line_buffer,sizeof(line_buffer), stdin)== NULL){
             is_invalid = 1;
         }
     }
     
 if(!is_invalid){
     char *token = strtok(line_buffer ,"\t\n");
     int score_val;
     while (token != NULL){
         if(score_count >= N){
             is_invalid = 1;
             break;
         }
     
         if(validate_and_parse(token,&score_val)){
             sum += score_val;
             score_count++;
         }
         else{
             is_invalid = 1;
             break;
         }
         token = strtok(NULL,"\t\n");
         }
         }
     if(!is_valid && score_count != N){
         is_invalid = 1;
     }
     if(is_invalid){
         printf("Invalid Input.\n");
     }
     else{
         double average = (double)sum/N;
         printf("%.2f\n"avergae);
     }
     return 0;