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


import java.util.*;
import java.lang.*;
import java.io.*;

public class TestClass {
	static FastReader sc;
	static int mod = (int) Math.pow(10, 9) + 7;
	static BufferedWriter log;
	static int size = 10000001;

	public static void main(String[] args) throws IOException {
		log = new BufferedWriter(new OutputStreamWriter(System.out));
		sc = new FastReader();
//		int t = sc.nextInt();
		int t = 1;
		for (int i_t = 0; i_t < t; i_t++) {
			long n=sc.nextLong();
			int m=sc.nextInt();
			long k=sc.nextLong();
			int[] dp=new int[100001];
			int max=0;
			for(int i=0;i<m;i++) {
				int tp=sc.nextInt();
				dp[tp]++;
				max=tp;
			}
			if(k>m)k=m;
			int ans = solve(n,m,(int)k,max,dp);
			log.write(ans + "\n");
//			log.write("Case #"+(i_t+1)+": " + ans + "\n");
		}
		log.flush();

	}

	

	private static int solve(long n, int m, int k, int max, int[] dp) {
		int l=1;int r=k;
		int ans=0;
		while(l<=max) {
			int count=0;
			for(int i=l;i<=r;i++) {
				if(dp[i]>0)count++;
			}
			l=r+1;
			if(count>0){
				r+=count;ans++;
			}
			else {
				r+=k;
			}
		}
		return ans;
	}



	private static void pL(long l) throws IOException {
		log.write(Long.toString(l) + "\n");
	}

	public static void pA(int[] a, int n) throws IOException {
		for (int i = 0; i < n; i++) {
			log.write(a[i] + " ");
		}
//		log.write("\n");
	}

	public static <T> void pA(T[] a, int n) throws IOException {
		for (int i = 0; i < n; i++) {
			log.write(a[i].toString() + "\n");
		}
		log.write("\n");
	}

	public static void pM(int[][] dp2, int n, int m) throws IOException {
		for (int i = 0; i < n; i++) {
			for (int j = 0; j < m; j++) {
				log.write(dp2[i][j] + " ");
			}
			log.write("\n");
		}
	}

	public static void pM(long[][] dp2, int n, int m) throws IOException {
		for (int i = 0; i < n; i++) {
			for (int j = 0; j < m; j++) {
				log.write(dp2[i][j] + " ");
			}
			log.write("\n");
		}
	}

}

class Card {
	public Card(int i, char charAt,String s) {
		x = i;
		ch = charAt;
		this.s=s;
	}

	int x;
	char ch;
	String s;
}

class FastReader {
	BufferedReader br;
	StringTokenizer st;

	public FastReader() {
	br=new  BufferedReader(new InputStreamReader(System.in));
	
	}

	String next() {
		while (st == null || !st.hasMoreElements()) {
			try {
				st = new StringTokenizer(br.readLine());
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		return st.nextToken();
	}

	int nextInt() {
		return Integer.parseInt(next());
	}

	long nextLong() {
		return Long.parseLong(next());
	}

	String nextLine() {
		String s = "";
		try {
			s = br.readLine();
		} catch (IOException e) {
			e.printStackTrace();
		}
		return s;
	}
}
