#include <bits/stdc++.h>
using namespace std;
int n, m, k;
vector<int> v[1000010];
vector<int> vv;
bool visit[1000010] = {0};
int t, tt;
int res = 0;
void dfs(int x) {
  visit[x] = 1;
  t++;
  for (int i = 0; i < v[x].size(); i++) {
    int xi = v[x][i];
    if (!visit[xi]) dfs(xi);
  }
}
int main() {
  scanf("%d%d%d", &n, &m, &k);
  for (int i = 0; i < m; i++) {
    int x, y;
    scanf("%d%d", &x, &y);
    x--, y--;
    v[x].push_back(y);
    v[y].push_back(x);
  }
  for (int i = 0; i < n; i++) {
    if (!visit[i]) {
      t = 0;
      dfs(i);
      vv.push_back(min(t, k));
    }
  }
  if (k == 1) {
    cout << max(0, (int)(vv.size() - 2));
    return 0;
  }
  sort(vv.begin(), vv.end());
  reverse(vv.begin(), vv.end());
  tt = vv[0];
  for (int i = 1; i < vv.size(); i++) {
    if (tt)
      tt += vv[i] - 2;
    else {
      tt++;
      res++;
    }
  }
  cout << res;
  return 0;
}
