import core.thread;
import std.conv, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.container, std.math, std.range, std.regex;

//	Input
class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { tokens = readln.split; if (stdin.eof) throw new EOFException; } auto token = tokens[0]; tokens.popFront; return token; }
int readInt() { return to!int(readToken); }
long readLong() { return to!long(readToken); }
real readReal() { return to!real(readToken); }

//	chmin/chmax
void chmin(T)(ref T t, in T f) { if (t > f) t = f; }
void chmax(T)(ref T t, in T f) { if (t < f) t = f; }

//	Pair
struct Pair(S, T) {
	S x; T y;
	int opCmp(    const Pair p) const { return (x < p.x) ? -1 : (x > p.x) ? +1 : (y < p.y) ? -1 : (y > p.y) ? +1 : 0; }
	int opCmp(ref const Pair p) const { return (x < p.x) ? -1 : (x > p.x) ? +1 : (y < p.y) ? -1 : (y > p.y) ? +1 : 0; }
	string toString() const { return "(" ~ to!string(x) ~ ", " ~ to!string(y) ~ ")"; }
}
auto pair(S, T)(inout(S) x, inout(T) y) { return Pair!(S, T)(x, y); }

//	Array
int binarySearch(T)(in T[] as, in bool delegate(T) test) { int low = -1, upp = as.length; for (; low + 1 < upp; ) { int mid = (low + upp) >> 1; (test(as[mid]) ? low : upp) = mid; } return upp; }
int lowerBound(T)(in T[] as, in T val) { return as.binarySearch((T a) { return (a <  val); }); }
int upperBound(T)(in T[] as, in T val) { return as.binarySearch((T a) { return (a <= val); }); }
T[] unique(T)(in T[] as) { T[] bs; foreach (a; as) if (bs.empty || bs[$ - 1] != a) bs ~= a; return bs; }


immutable INF = 1_000_000_000;

int N, M, K;
int[] A, B;

void main(string[] args) {
	try {
	for (; ; ) {
		N = readInt;
		M = readInt;
		K = readInt;
		A = new int[M];
		B = new int[M];
		foreach (i; 0 .. M) {
			A[i] = readInt - 1;
			B[i] = readInt - 1;
		}
		
		int[][] d = new int[][](N, N);
		foreach (u; 0 .. N) {
			d[u][] = INF;
			d[u][u] = 0;
		}
		foreach (i; 0 .. M) {
			chmin(d[A[i]][B[i]], 1);
			chmin(d[B[i]][A[i]], 1);
		}
		foreach (w; 0 .. N) foreach (u; 0 .. N) foreach (v; 0 .. N) {
			chmin(d[u][v], d[u][w] + d[w][v]);
		}
		
		int[] us;
		
		bool check() {
debug{
writeln("check us = ",us);
}
			if (us.length > K) {
				return false;
			}
			int[][] dp = new int[][](1 << us.length, us.length);
			foreach (h; 0 .. 1 << us.length) {
				dp[h][] = INF;
			}
			foreach (a, u; us) {
				dp[1 << a][a] = d[0][u];
			}
			foreach (h; 0 .. 1 << us.length) foreach (a, u; us) {
				foreach (b, v; us) {
					chmin(dp[h | 1 << b][b], dp[h][a] + d[u][v]);
				}
			}
			foreach (a, u; us) {
				if (dp[(1 << us.length) - 1][a] <= K) {
					return true;
				}
			}
			return false;
		}
		
		foreach_reverse (u; 1 .. N) {
			us ~= u;
			if (!check) {
				us.popBack;
			}
		}
		long ans;
		foreach (u; us) {
			ans += (1L << u) - 1;
		}
		writeln(ans);
	}
	} catch (EOFException) {}
}