content: package v110;
  	
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStreamReader;
  import java.util.StringTokenizer;
  public class JustFinishItUp_UVa11093{
  	
  	public static void main(String[] args) throws IOException
  	{
  		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
  		StringBuilder sb = new StringBuilder();
  		int t = Integer.parseInt(new StringTokenizer(br.readLine()).nextToken());
  		
  		for(int i = 1; i <= t; i++)
  		{
  			int n = Integer.parseInt(new StringTokenizer(br.readLine()).nextToken());
  			StringTokenizer st;
  			int sumP = 0;int[] ps = new int[n];
  			st = new StringTokenizer(br.readLine());
  			for(int j = 0; j < n; j++)
  			{
  				if(!st.hasMoreTokens())
  				{
  					st = new StringTokenizer(br.readLine());	
  				}
  				ps[j] = Integer.parseInt(st.nextToken());
  				sumP += ps[j];
  			}
  			int sumQ = 0; int[] qs = new int[n];
  			
  			for(int j = 0; j < n; j++)
  			{
  				if(!st.hasMoreTokens())
  				{
  					st = new StringTokenizer(br.readLine());	
  				}
  				qs[j] = Integer.parseInt(st.nextToken());
  				sumQ += qs[j];
  			}		
  			if(sumQ>sumP)
  				sb.append("Case "+i+": Not possible\n");
  			else
  			{
  				int start = 0; int tank = 0; 
  				for(int j = 0; j < n; j++)
  				{
  					tank += ps[j] - qs[j];
  					if(tank<0)
  					{
  						tank = 0;start = j + 1;
  					}
  				}
  				
  				sb.append("Case "+i+": Possible from station "+(++start)+"\n");
  			}
  		}
  		
  		System.out.print(sb);
  	}
  	
  }	