#include<bits/stdc++.h>
using namespace std;


int main()
{
    int c,s,i,j,k,test=1;
    while(cin>>c>>s)
    {
        int arr[2*c+5],sum=0;
        vector<int>v;
        for(i=0; i<s; i++)
        {
            cin>>arr[i];
            sum+=arr[i];
        }
        while(s<2*c)
        {
            arr[i++]=0;
            s++;
        }
        sort(arr,arr+i);
        i--;
        double avg=(double)sum/(double)c;
        double im=0.0;
        cout<<"Set #"<<test++<<endl;
        for(j=0,k=i;j<c;j++,k--)
        {
             printf("%2d:",j);
             if(arr[j])cout<<" "<<arr[j];
             if(arr[k])cout<<" "<<arr[k];
             im+=abs(avg-(arr[j]+arr[k]));
             cout<<endl;
        }
        printf("IMBALANCE = %.5lf\n",im);
        cout<<endl;
    }
    return 0;
}