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

// A U T H O R : s a n 1 d h y a

public class cf1191A {
	static long Mod1 = 1000000007;

	static 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 ni() {
			return Integer.parseInt(next());
		}

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

		double nd() {
			return Double.parseDouble(next());
		}

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

	/*
	 * public static void sortbyColumn(int arr[][], int col) { // Using built-in
	 * sort function Arrays.sort Arrays.sort(arr, new Comparator<int[]>() {
	 * 
	 * @Override // Compare values according to columns public int compare(final
	 * int[] entry1, final int[] entry2) {
	 * 
	 * // To sort in descending order revert // the '>' Operator if (entry1[col] >
	 * entry2[col]) return 1; else return -1; } }); // End of function call sort().
	 * }
	 */
/*	public static long binex(long x, long y) {
		x = x % Mod1;
		long ret = 1;
		while (y > 0) {
			if (y % 2 != 0) {
				ret = ret * x % Mod1;
			}
			x = x * x % Mod1;
			y >>= 1;
		}
		return ret;
	}
*/
/*	public static long mplr(long x, long y) {
		long ret = 0;
		while (y != 0) {
			if (y % 2 != 0) {
				ret = (ret + x) % Mod1;
			}
			x = (x + x) % Mod1;
			y >>= 1;
		}
		return ret;
	}
*/
	public static void main(String[] args) {
		FastReader sc = new FastReader();
		long n = sc.nl();
		int m=sc.ni();
		long p[]=new long[m+1];
		long k=sc.nl();
		long o=0;
		long c=k;
		long s=0;
		for(int i=0;i<m;i++)
	{	
			p[i]=sc.nl();
	}
		p[m]=Integer.MAX_VALUE;
		for(int i=0;i<m+1;i++) {
			if(p[i]<=c)
				s++;
			else if(p[i]>n)
			{
				s=0;
				break;
				
			}
			else
			{	
				o++;
				if(s!=0)
				c+=s;
				else
					c+=k;
				
				s=0;
				i--;
			}
		}
	//	System.out.println(s+" "+c);
		if(s==0)
		System.out.println(o);
		else
			System.out.println(o+1); 
	}
}