// editor2
#include<iostream>
#include<string>
#include<vector>
#include<iomanip>
using namespace std;
class Employee
{
    private:
    string nameID;
    int numlogs;
    double totalHours=0,totalTasks=0;
    bool isValid =true;
    public:
    Employee(string id,int n): nameID(id),numlogs(n)
    {
      if(n<1||n>10) 
      isValid=false;
    }
    void addLog(int hours,int task)
    {
        if(hours<1||hours>24||task<0||task>100)
        {
            isValid=false;
        }
        totalHours+=hours;
        totalTasks+=task;
    }
    static void dispalyAverage(const Employee& e)
    {
        if(!e.isValid||e.totalHours==0)
        {
            cout<<"Invalid input"<<endl;
        }
        else
        {
            cout<<fixed<<setprecision(2)<<(e.totalTasks/e.totalHours);
        }
    }
};
int main()
{
    string id;
    int n;
    if(!(cin>>id>>n))
    return 0;
    Employee emp(id,n);
    for(int i=0;i<n;i++)
    {
        int h,t;
        cin>>h>>t;
    {
        emp.addLog(h,t);
    }
    }
    emp::displayAverage(emp);
    return 0;
}