import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.InputMismatchException;

public class Main {
	static InputStream is;
	static PrintWriter out;
	static String INPUT = "";
	
	static void solve()
	{
		int n = ni(), m = ni(), K = ni();
		int[] from = new int[m];
		int[] to = new int[m];
		int[][] g = new int[n][n];
		for(int i = 0;i < n;i++){
			Arrays.fill(g[i], 999999);
			g[i][i] = 0;
		}
		for(int i = 0;i < m;i++){
			from[i] = ni()-1;
			to[i] = ni()-1;
			g[from[i]][to[i]] = g[to[i]][from[i]] = 1;
		}
		for (int k = 0; k < n; k++) {
			for (int i = 0; i < n; i++) {
				for (int j = 0; j < n; j++) {
					if (g[i][j] > g[i][k] + g[k][j]) {
						g[i][j] = g[i][k] + g[k][j];
					}
				}
			}
		}
		
		long ptn = 1;
		long ret = 0;
		for(int i = n-1;i >= 1;i--){
			if(Long.bitCount(ptn) >= K+1)break;
			if(dist(ptn|1L<<i, g) <= K){
				ptn |= 1L<<i;
				ret += (1L<<i)-1;
			}
		}
		out.println(ret);
	}
	
	static int dist(long ptn, int[][] g)
	{
		int n = g.length;
		int[] map = new int[Long.bitCount(ptn)];
		int p = 0;
		for(int i = 0;i < n;i++){
			if(ptn<<~i<0){
				map[p++] = i;
			}
		}
		int u = map.length;
		int[][] dp = new int[1<<u][u];
		for(int i = 0;i < 1<<u;i++){
			Arrays.fill(dp[i], Integer.MAX_VALUE / 3);
		}
		dp[1][0] = 0;
		for(int i = 2;i < 1<<u;i++){
			for(int j = 0;j < u;j++){
				if(i<<~j<0){
					for(int k = 0;k < u;k++){
						if(k != j && i<<~k<0){
							dp[i][j] = Math.min(dp[i][j], dp[i^1<<j][k] + g[map[k]][map[j]]);
						}
					}
				}
			}
		}
		int min = Integer.MAX_VALUE / 3;
		for(int i = 0;i < u;i++){
			min = Math.min(min, dp[(1<<u)-1][i]);
		}
		return min;
	}
	
	static int[][] packU(int n, int[] from, int[] to) {
		int[][] g = new int[n][];
		int[] p = new int[n];
		for (int f : from)
			p[f]++;
		for (int t : to)
			p[t]++;
		for (int i = 0; i < n; i++)
			g[i] = new int[p[i]];
		for (int i = 0; i < from.length; i++) {
			g[from[i]][--p[from[i]]] = to[i];
			g[to[i]][--p[to[i]]] = from[i];
		}
		return g;
	}
	
	public static void main(String[] args) throws Exception
	{
		long S = System.currentTimeMillis();
		is = INPUT.isEmpty() ? System.in : new ByteArrayInputStream(INPUT.getBytes());
		out = new PrintWriter(System.out);
		
		solve();
		out.flush();
		long G = System.currentTimeMillis();
		tr(G-S+"ms");
	}
	
	private static boolean eof()
	{
		if(lenbuf == -1)return true;
		int lptr = ptrbuf;
		while(lptr < lenbuf)if(!isSpaceChar(inbuf[lptr++]))return false;
		
		try {
			is.mark(1000);
			while(true){
				int b = is.read();
				if(b == -1){
					is.reset();
					return true;
				}else if(!isSpaceChar(b)){
					is.reset();
					return false;
				}
			}
		} catch (IOException e) {
			return true;
		}
	}
	
	private static byte[] inbuf = new byte[1024];
	static int lenbuf = 0, ptrbuf = 0;
	
	private static int readByte()
	{
		if(lenbuf == -1)throw new InputMismatchException();
		if(ptrbuf >= lenbuf){
			ptrbuf = 0;
			try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); }
			if(lenbuf <= 0)return -1;
		}
		return inbuf[ptrbuf++];
	}
	
	private static boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); }
	private static int skip() { int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; }
	
	private static double nd() { return Double.parseDouble(ns()); }
	private static char nc() { return (char)skip(); }
	
	private static String ns()
	{
		int b = skip();
		StringBuilder sb = new StringBuilder();
		while(!(isSpaceChar(b))){ // when nextLine, (isSpaceChar(b) && b != ' ')
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}
	
	private static char[] ns(int n)
	{
		char[] buf = new char[n];
		int b = skip(), p = 0;
		while(p < n && !(isSpaceChar(b))){
			buf[p++] = (char)b;
			b = readByte();
		}
		return n == p ? buf : Arrays.copyOf(buf, p);
	}
	
	private static char[][] nm(int n, int m)
	{
		char[][] map = new char[n][];
		for(int i = 0;i < n;i++)map[i] = ns(m);
		return map;
	}
	
	private static int[] na(int n)
	{
		int[] a = new int[n];
		for(int i = 0;i < n;i++)a[i] = ni();
		return a;
	}
	
	private static int ni()
	{
		int num = 0, b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private static long nl()
	{
		long num = 0;
		int b;
		boolean minus = false;
		while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
		if(b == '-'){
			minus = true;
			b = readByte();
		}
		
		while(true){
			if(b >= '0' && b <= '9'){
				num = num * 10 + (b - '0');
			}else{
				return minus ? -num : num;
			}
			b = readByte();
		}
	}
	
	private static void tr(Object... o) { if(INPUT.length() != 0)System.out.println(Arrays.deepToString(o)); }
}