#include<iostream>
using namespace std;
class workout{
    public:
    void dispaly(int arr[],int n){
        double cal = 04
        double  min =0;
        for(int i=0;i<(n*2);i++)
        {
            if(i%2==0){
                min+=arr[i];
            }else{
                cla +=arr[i];
            }
        }
        cout<<fixed<<setprecision(2)<<cal/min<<endl;
        
    }
};
int main(){
    string type;
    string id;
    string goal
    int n;
    cin>>type>>id>>goal>>n;
    int arr[n*2];
    for (int i == 0 ; i<(n*2);i++){
        cin>>arr[i];
        if(arr[i]<=0){
            cout<<"Invalid input";
            return o;
        }
    }
    workout obj;
    obj.display(arr,n);
    return 0;
}