import java.io.*;
import java.math.*;
import java.util.*;

import static java.util.Arrays.*;

public class H {
	private static final int mod = (int)1e9+7;

	final Random random = new Random(0);
	final IOFast io = new IOFast();

	/// MAIN CODE
	public void run() throws IOException {
//		int TEST_CASE = Integer.parseInt(new String(io.nextLine()).trim());
		int TEST_CASE = 1;
		while(TEST_CASE-- != 0) {
			n = io.nextInt();
			int m = io.nextInt();
			int K = io.nextInt();
			
			dp = new int[n][n];
			for(int i = 0; i < n; i++) {
				Arrays.fill(dp[i], 1<<29);
				dp[i][i] = 0;
			}
			for(int i = 0; i < m; i++) {
				int s = io.nextInt() - 1;
				int t = io.nextInt() - 1;
				dp[s][t] = dp[t][s] = 1;
			}
			for(int k = 0; k < n; k++)
				for(int i = 0; i < n; i++)
					for(int j = 0; j < n; j++)
						dp[i][j] = Math.min(dp[i][j], dp[i][k] + dp[k][j]);
			
			long ans = 0;
			long h = 1;
			for(int i = n - 1; i > 0; i--) {
				if(can(h|1L<<i, K)) {
					ans += (1L<<i) - 1;
					h |= 1L<<i;
				}
			}
//			System.err.println(Arrays.toString(Arrays.copyOf(curP, len)));
			
			io.out.println(ans);
		}
	}

	int n;
	int[][] dp;
	int[][] dp2 = new int[15][1<<15];
	int gid;
	int[][] id = new int[15][1<<15];
	boolean can(long h, int K) {
		int[] pos = new int[Long.bitCount(h)];
		for(int i = 0, j = 0; i < n; i++) if((h>>>i&1) == 1) pos[j++] = i;
//		int[][] dp2 = new int[pos.length][1<<pos.length];
//		for(int[] d : dp2) Arrays.fill(d, 1<<29);
		gid++;
		id[0][1] = gid;
		dp2[0][1] = 0;
		
		for(int j = 0; j < 1 << pos.length; j++) {
			for(int i = 0; i < pos.length; i++) if((j>>i&1) == 0) {
				for(int k = 0; k < pos.length; k++) if((j>>k&1) == 1) {
//					System.err.println(i + " " + j + " " + k + " " + dp2.length + " " + dp2[0].length);
					if(id[i][j|1<<i] != gid) { id[i][j|1<<i] = gid; dp2[i][j|1<<i] = 1<<29; }
					if(id[k][j] != gid) { id[k][j] = gid; dp2[k][j] = 1<<29; }
					dp2[i][j|1<<i] = Math.min(dp2[i][j|1<<i], dp2[k][j] + dp[pos[k]][pos[i]]);
				}
			}
		}
		for(int i = 0; i < pos.length; i++) {
			if(dp2[i][(1<<pos.length)-1] <= K) {
//				System.err.println(i + " " + ((1<<pos.length)-1) + " " + dp2[i][(1<<pos.length)-1]);
				return true;
			}
		}
		return false;
	}
	
	
	static
	class UnionFind {
		private int[] data;
		
		public UnionFind(int size) {
			data = new int[size];
			clear();
		}
		
		public UnionFind(final UnionFind uf) {
			data = uf.data.clone();
		}
		
		public void clear() {
			Arrays.fill(data, -1);
		}
		
		public int root(int x) { return data[x] < 0 ? x : (data[x] = root(data[x])); }
		
		public void union(int x, int y) {
			if((x = root(x)) != (y = root(y))) {
				if(data[y] < data[x]) { final int t = x; x = y; y = t; }
				data[x] += data[y];
				data[y] = x;
			}
		}
		
		public boolean same(int x, int y) { return root(x) == root(y); }
		public int size(int x) { return -data[root(x)]; }
	}


	/// TEMPLATE
	static int gcd(int n, int r) { return r == 0 ? n : gcd(r, n%r); }
	static long gcd(long n, long r) { return r == 0 ? n : gcd(r, n%r); }
	
	static <T> void swap(T[] x, int i, int j) { T t = x[i]; x[i] = x[j]; x[j] = t; }
	static void swap(int[] x, int i, int j) { int t = x[i]; x[i] = x[j]; x[j] = t; }
	
	void main() throws IOException {
		//		IOFast.setFileIO("rle-size.in", "rle-size.out");
		try { run(); }
		catch (EndOfFileRuntimeException e) { }
		io.out.flush();
	}
	public static void main(String[] args) throws IOException { new H().main(); }
	
	static class EndOfFileRuntimeException extends RuntimeException {
		private static final long serialVersionUID = -8565341110209207657L; }

	static
	public class IOFast {
		private BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
		private PrintWriter out = new PrintWriter(System.out);

		void setFileIn(String ins) throws IOException { in.close(); in = new BufferedReader(new FileReader(ins)); }
		void setFileOut(String outs) throws IOException { out.flush(); out.close(); out = new PrintWriter(new FileWriter(outs)); }
		void setFileIO(String ins, String outs) throws IOException { setFileIn(ins); setFileOut(outs); }

		private static int pos, readLen;
		private static final char[] buffer = new char[1024 * 8];
		private static char[] str = new char[500*8*2];
		private static boolean[] isDigit = new boolean[256];
		private static boolean[] isSpace = new boolean[256];
		private static boolean[] isLineSep = new boolean[256];

		static { for(int i = 0; i < 10; i++) { isDigit['0' + i] = true; } isDigit['-'] = true; isSpace[' '] = isSpace['\r'] = isSpace['\n'] = isSpace['\t'] = true; isLineSep['\r'] = isLineSep['\n'] = true; }
		public int read() throws IOException { if(pos >= readLen) { pos = 0; readLen = in.read(buffer); if(readLen <= 0) { throw new EndOfFileRuntimeException(); } } return buffer[pos++]; }
		public int nextInt() throws IOException { int len = 0; str[len++] = nextChar(); len = reads(len, isSpace); int i = 0; int ret = 0; if(str[0] == '-') { i = 1; } for(; i < len; i++) ret = ret * 10 + str[i] - '0'; if(str[0] == '-') { ret = -ret; } return ret; }
		public long nextLong() throws IOException { int len = 0; str[len++] = nextChar(); len = reads(len, isSpace); int i = 0; long ret = 0; if(str[0] == '-') { i = 1; } for(; i < len; i++) ret = ret * 10 + str[i] - '0'; if(str[0] == '-') { ret = -ret; } return ret; }
		public char nextChar() throws IOException { while(true) { final int c = read(); if(!isSpace[c]) { return (char)c; } } }
		int reads(int len, boolean[] accept) throws IOException { try { while(true) { final int c = read(); if(accept[c]) { break; } if(str.length == len) { char[] rep = new char[str.length * 3 / 2]; System.arraycopy(str, 0, rep, 0, str.length); str = rep; } str[len++] = (char)c; } } catch(EndOfFileRuntimeException e) { ; } return len; }
		int reads(char[] cs, int len, boolean[] accept) throws IOException { try { while(true) { final int c = read(); if(accept[c]) { break; } cs[len++] = (char)c; } } catch(EndOfFileRuntimeException e) { ; } return len; }
		public char[] nextLine() throws IOException { int len = 0; str[len++] = nextChar(); len = reads(len, isLineSep); try { if(str[len-1] == '\r') { len--; read(); } } catch(EndOfFileRuntimeException e) { ; } return Arrays.copyOf(str, len); }
		public String nextString() throws IOException { return new String(next()); }
		public char[] next() throws IOException { int len = 0; str[len++] = nextChar(); len = reads(len, isSpace); return Arrays.copyOf(str, len); }
		public int next(char[] cs) throws IOException { int len = 0; cs[len++] = nextChar(); len = reads(cs, len, isSpace); return len; }
		public double nextDouble() throws IOException { return Double.parseDouble(nextString()); }
		public long[] nextLongArray(final int n) throws IOException { final long[] res = new long[n]; for(int i = 0; i < n; i++) { res[i] = nextLong(); } return res; }
		public int[] nextIntArray(final int n) throws IOException { final int[] res = new int[n]; for(int i = 0; i < n; i++) { res[i] = nextInt(); } return res; }
		public int[][] nextIntArray2D(final int n, final int k) throws IOException { final int[][] res = new int[n][]; for(int i = 0; i < n; i++) { res[i] = nextIntArray(k); } return res; }
		public int[][] nextIntArray2DWithIndex(final int n, final int k) throws IOException { final int[][] res = new int[n][k+1]; for(int i = 0; i < n; i++) { for(int j = 0; j < k; j++) { res[i][j] = nextInt(); } res[i][k] = i; } return res; }
		public double[] nextDoubleArray(final int n) throws IOException { final double[] res = new double[n]; for(int i = 0; i < n; i++) { res[i] = nextDouble(); } return res; }
	}
}