content: package v120;
  
  import java.io.BufferedReader;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.InputStreamReader;
  import java.io.PrintWriter;
  import java.util.StringTokenizer;
  
  
  public class TheMonkeyAndTheOiledBamboo_UVa12032 {
  
  	public static void main(String[] args) throws IOException 
  	{
  		Scanner sc = new Scanner(System.in);
  		PrintWriter out = new PrintWriter(System.out);
  		
  		int tc = sc.nextInt();
  		for(int t = 1; t <= tc; ++t)
  		{
  			int n = sc.nextInt(), h[] = new int[n];
  			for(int i = 0; i < n; ++i)
  				h[i] = sc.nextInt();
  			int ans = -1, lo = 1, hi = (int)1e7;
  			while(lo <= hi)
  			{
  				int mid = lo + hi >> 1;
  				if(possible(n, h, mid))
  				{
  					ans = mid;
  					hi = mid - 1;
  				}
  				else
  					lo = mid + 1;
  			}
  			out.printf("Case %d: %d\n", t, ans);
  		}
  		out.flush();
  		out.close();
  	}
  	
  	static boolean possible(int n, int[] h, int k)
  	{
  		int cur = 0;
  		for(int i = 0; i < n; ++i)
  			if(cur + k < h[i])
  				return false;
  			else
  			{
  				if(cur + k == h[i])
  					--k;
  				cur = h[i];
  			}
  		return true;
  	}
  
  	static class Scanner
  	{
  		StringTokenizer st;
  		BufferedReader br;
  
  		public Scanner(InputStream s){	br = new BufferedReader(new InputStreamReader(s));}
  
  		public String next() throws IOException 
  		{
  			while (st == null || !st.hasMoreTokens()) 
  				st = new StringTokenizer(br.readLine());
  			return st.nextToken();
  		}
  
  		public int nextInt() throws IOException {return Integer.parseInt(next());}
  
  		public long nextLong() throws IOException {return Long.parseLong(next());}
  
  		public String nextLine() throws IOException {return br.readLine();}
  
  		public double nextDouble() throws IOException
  		{
  			return Double.parseDouble(next());
  		}
  
  		public boolean ready() throws IOException {return br.ready();}
  
  
  	}
  }