#include<cstdio>
#include<iostream>
#include<vector>
#include<algorithm>
#include<string>
#include<cstring>
using namespace std;

typedef long long LL;
typedef vector<int> VI;

#define REP(i,n) for(int i=0; i<int(n); i++)
#define EACH(i,c) for(__typeof((c).begin()) i=(c).begin();i!=(c).end();i++)

template<class T> inline T &amin(T &a, T b) { if (a>b) a=b; return a; }
template<class T> inline T &amax(T &a, T b) { if (a<b) a=b; return a; }


int N, M, K;
int FW[60][60];

void init() {
    scanf("%d%d%d", &N, &M, &K);
    memset(FW, 0x3f, sizeof FW);
    REP (i, M) {
	int x, y;
	scanf("%d%d", &x, &y);
	x--; y--;
	FW[x][y] = FW[y][x] = 1;
    }
    REP (i, N) FW[i][i] = 0;
}

int dp[1<<16][16];
int cost(vector<int> v) {
    int N = v.size();
    memset(dp, 0x3f, sizeof dp);
    dp[1][0] = 0;
    REP (S, 1<<N) {
	REP (i, N) if (S & (1<<i)) { // from
	    REP (j, N) {
		amin(dp[S | (1<<j)][j], dp[S][i] + FW[v[i]][v[j]]);
	    }
	}
    }

    int ans = dp[(1<<N)-1][0];
    REP (i, N) amin(ans, dp[(1<<N)-1][i]);
    return ans;
}

int main() {
    init();
    REP (k, N) REP (i, N) REP (j, N) amin(FW[i][j], FW[i][k]+FW[k][j]);
    // REP (i, N) {
    // 	REP (j, N) {
    // 	    cerr << FW[i][j] << ' ';;
    // 	}
    // 	cerr << endl;
    // }
	    

    vector<int> v(1, 0);
    for (int i=N-1; i>0; i--) {
	v.push_back(i);
	int tmp = cost(v);

	if (tmp > K) v.pop_back();
	if (v.size() == 16u) break;
    }

    LL ans = 0;

    REP (i, v.size()) ans += (1LL<<v[i])-1;
    cout << ans << endl;
    return 0;
}