10 5 5
2 3 4 5 6
 1 1 1
1
 1000000000000000000 10 68
9818112234872670 233245257111863071 266483628625876079 375103213040049805 431982380866113633 489732004669478331 501030096787260719 541800997319766183 551892546260532408 696178619227890200
 1000000000000000000 2 1
1 1000000000000000000
 33 32 1
1 2 3 4 5 6 7 8 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33
 101 55 10
1 3 5 7 8 9 10 16 18 21 22 23 24 25 27 30 32 35 36 37 38 39 40 43 45 47 49 50 51 52 54 57 59 61 64 66 67 68 69 70 71 72 73 80 83 86 87 88 89 90 91 92 96 97 98
 1000000000000000000 5 1000
1 1000000000 1000000000000 1000000000000000 1000000000000001
 15 15 15
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15
 21 21 20
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
 45 43 2
1 2 3 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45
 107 20 13
5 9 20 25 26 30 37 45 51 58 62 73 82 87 89 90 99 101 104 106
 3 2 1
1 2
 1000000000 2 1000000000
1 1000000000
 11 7 3
2 3 4 5 6 7 11
 13 9 4
1 2 3 6 7 8 11 12 13
 1000000000000000000 2 1000000000
102306300054748096 267367244641009859
 16 7 5
2 3 4 5 6 15 16
 35 35 1
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35
 1000000000000000000 20 365
31881893160049984 103938857870698567 103962228223609431 140762820261865064 175962215264653912 239086305245565642 354522451098745823 383839975876242372 443471287955807705 478923027151493682 511195154588214957 619570919279066139 677571312513476877 705864797651447277 789633853044745934 867300890280086078 883297431113041450 891736036124527038 937306858250803630 990892290394455512

2
 1
 10
 2
 32
 15
 4
 1
 2
 35
 9
 2
 1
 4
 4
 2
 4
 35
 20

/*input

13 4 5
7 8 9 10



*/
import java.io.*;
import java.util.*;
 
 
public class mymy
{
 
	static OutputStream outputStream = System.out;
	static PrintWriter out = new PrintWriter(outputStream);	
	static InputStream inputStream = System.in;
	static InputReader br = new InputReader(inputStream);

	

	
	public static void main(String[] args)throws IOException
	{
 
		long n=br.nextLong();
		int m=br.nextInt();
		long k=br.nextLong();

		Queue<Long> q=new LinkedList<Long>();

		for(int i=0;i<m;i++) q.add(br.nextLong());

		long op=0,curr=k;

		long div=n/k;div++;

		long add=0;

		while(q.size()>0)
		{
			while(q.size()>0 && q.peek()<=curr)
			{
				q.poll();
				add++;
			}
			if(add==0)
			{
				if(q.size()>0)
				{
					long where=q.peek();

					long low=0,high=div,ans=-1;

					while(low<=high)
					{
						long mid=(low+high)/2;

						if(curr+(mid*k)>=where)
						{
							ans=mid;
							high=mid-1;
						}
						else low=mid+1;
					}
					curr+=ans*k;
				}
			}
			else
			{
				curr+=add;
				add=0;
				op++;
			}
		}


		out.println(op);



		





		
 
		out.close();
 
	}
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
	static class InputReader {
		public BufferedReader reader;
		public StringTokenizer tokenizer;
 
		public InputReader(InputStream stream) {
			reader = new BufferedReader(new InputStreamReader(stream), 32768);
			tokenizer = null;
		}
 
		public String next() {
			while (tokenizer == null || !tokenizer.hasMoreTokens()) {
				try {
					tokenizer = new StringTokenizer(reader.readLine());
				} catch (IOException e) {
					throw new RuntimeException(e);
				}
			}
			return tokenizer.nextToken();
		}
 
		public int nextInt() {
			return Integer.parseInt(next());
		}
		public long nextLong() {
			return Long.parseLong(next());
		}
 
	}
	
}