#include<iostream>
#include<iomanip>
#include<string>
using namespace std;
class e{
    private:
    string name;
    string id;
    int logs;
    double th,tt;
    public:
    e(string n,string i, int 1){
        name = n;
        id = i;
        logs = 0;
        th = 0;
        tt = 0;
    }
    bool addlog(int hour, int task){
        if( hour <1 || hour >24 || task <0 || task >1000){
            return false;
        }
        th += hours;
        tt += task;
        return true;
    }
    static void displayavarage(e m){
        if(m.th == 0){
            cout<<"Invalid input"<<endl;
        }
        else{
            double avg = m.tt / m.th;
            cout<<fixed<<setprecision(2)<<avg<<endl;
        }
    }
};
int main()
{
    string name, id;
    int log;
    cin>>name>>id>>logs;
    if(logs <1 || logs>10)
    {
        cout<<"Invalid input"<<endl;
        return 0;
    }
    e emp(name,id,logs);
    for(int i =0;i<logs;i++){
        int hours,task;
        cin>>hours>>tasks;
        if(!emp.addlog(hours,tasks)){
            cout<<"Invalid input"<<endl;
            return 0;
        }
    }
    e::displayaverage(emp);
    return 0;
}