111

#include <bits/stdc++.h>
using namespace std;
int main(){
    int k;
    cin>>k;
    for(int x = 1;x<=k;x++){
        int w,s;
        cin>>w>>s;
        double n[s+5],v[s+5];
        double sum = 0;
        for(int i = 1;i<=s;i++){
            cin>>n[i]>>v[i];
        }
        for(int i = 1;i<s;i++){
            for(int j = i+1;j<=s;j++){
                if(v[i]/n[i]<v[j]/n[j]){
                    swap(v[i],v[j]);
                    swap(n[i],n[j]);
                }
            }
        }
        for(int i = 1;i<=s;i++){
            cout<<n[i]<<" "<<v[i]<<endl;
        }
        int i = 1;
        while(w>0){
            if(w>n[i]){
                sum += v[i];
                w -= n[i];
            }else{
                sum += w/n[i]*v[i];
                w = 0;
            }
        }
        cout<<sum<<endl;
    }
    return 0;
}