#include<iostream>
#include<iomanip>
using namespace std;
class Employee{
private:
   string name,id;
   int logs;
   float totalHours=0,totalTasks=0;
public:
    void input(){
    cin>>name>>id>>logs;
    if (logs<1||logs>10){
        cout<<"Invalid input";
        exit(0);
    }
    for(int i=0;i<logs;i++){
        float hours,tasks;
        cin>>hours>>tasks;
        if(hours<1||hours>24||tasks<0||tasks>100){
            cout<<"Invalid input";
            exit(0);
        }
        totalHours+=hours;
        totalTasks+=tasks;
    }
}
static void display(float avg){
    cout<<fixed<<setprecision(2)<<avg;
}
float calculateAverage(){
    if(totalHours==0)return 0;
    return totalTasks/totalHours;}};
int amin(){
    Employee emp;
    emp.input();
    float avg=emp.calculateAverage();
    Employee::display(avg);
    return 0;
}