#include<iostream>
#include<iomanip>
#include<string>
using namespace std;

class user
{
    protected:
    string usertype;
    string userid;
    
    public:
    user(const string type,const string id) : usertype(type),userid(id) {}
};

class workoutuser: public user
{
    private:
    string goal;
    
    public:
    workoutuser(const string type, const string id, const string g) : user(type,id), goal(g); {}
    
    double acpm(int logs)
    {
        double totalduration=0.0;
        double totalcalories=0.0;
        for(int i=0;i<logs;i++)
        {
            double duration, calories;
            if(!(cin>>duration>>calories)||duration<0.0||duration>1000.0||calories<0.0||calories>1000.0)
            {
                cout<<"Invalid input";
                return 0;
            }
            totalduration+=duration;
            totalcalories+=calories;    
        }
        if(totalduration<0.0)
        {
            cout<<"Invalid input";
            return 0;
        }
        else
        {
            return totalcalories/totalduration;
        }
    };
}
int main()
{
    ios:sync_with_stdio(false);
    cin.tie(nullptr);
    
    string type,id;
    if(!(cin>>type>>id))
    {
        cout<<"Invalid input";
        return 0;
    }
    string goal;
    int logs;
    if(!(cin>>goal>>logs)||logs<1||logs>10)
    {
        cout<<"Invalid input";
        return 0;
    }
    workoutuser user(type,id,goal);
    double avg=user.acpm(logs);
    if(avg<0.0)
    {
        cout<<"Invalid input";
        return 0;
    }
    cout<<fixed<<setprecision(2)<<avg;
    return 0;
    }
}