#include<iostream>
#include<iomanip>
#include<string>
using namespace std;
class FitnessApp{
    string userType;
    string userID;
    string goal;
    int logs;
    double totalDuration = 0;
    double totalCalories = 0;
    
    public:
    void getInput(){
        cin>>userType>>userID;
        cin>>goal>>logs;
        for(int i=0;i<logs;i++)
        {
            double duration,calories;
            cin>>duration>>caloried;
            if(duration<=0||calories<=0){
                cout<<"Invalid input";
                exit(0);
            }
            totalDuration+=duration;
            totalCalories+=calories;
        }
    }
    void calculateAverage(){
        if(totalDuration>0){
            double avg=totalCalories/totalDuration;
            cout<<fixed<<setprecision(2)<<avg;
        }
    }
};
int main()
{
    FitnessApp obj;
    obnj.getInput();
    obj.calculateAverage();
    return 0;
}