Problem p02688 (C++) — buggy submission, verdict: Runtime Error

#include <bits/stdc++.h>

using namespace std;

#define REP1(i, n) for (int i = 1, i##_len = (n); i < i##_len; ++i)
#define REP(i, n) for (int i = 0, i##_len = (n); i < i##_len; ++i)
#define pow(x) x *x
#define ll long long
static const ll MAX = 1000000;
static const ll INFTY = 1e12;
static const ll MOD = 1000000007;

template <typename T> inline string toString(const T &a) {
  ostringstream oss;
  oss << a;
  return oss.str();
};

struct edge {
  ll to, cost;
};

using Graph = vector<vector<int>>;
using _Graph = vector<vector<edge>>;

const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};

// 深さ優先探索
vector<bool> seen;
vector<int> colors;

// int H, W, N;
int sx, sy, gx, gy;
vector<vector<char>> field;
vector<vector<int>> dist;
// vector<pair<int, int>> gx, gy;
deque<pair<int, int>> que;

typedef vector<vector<int>> Matrix;

const int INF = 100000000;

int main() {

  int N, K;
  cin >> N >> K;
  vector<int> d(K);
  // vector<vector<int>> A(K);
  vector<bool> su(N, false);
  REP(i, K) {
    cin >> d[i];
    REP(j, d[i]) {
      int a;
      cin >> a;
      a--;
      // A[j].push_back(a);
      su[a] = true;
    }
  }
  int count = 0;
  REP(i, N) {
    if (su[i] == false) {
      count++;
    }
  }

  cout << count << endl;
}

/*
                   _ooOoo_
                  o8888888o
                  88" . "88
                  (| -_- |)
                  O\\  =  /O
               ____/`---'\\____
             .'  \\\\|     |//  `.
            /  \\\\|||  :  |||//  \\
           /  _||||| -:- |||||-  \\
           |   | \\\\\\  -  /// |   |
           | \\_|  ''\\---/''  |   |
           \\  .-\\__  `-`  ___/-. /
         ___`. .'  /--.--\\  `. . __
      ."" '<  `.___\\_<|>_/___.'  >'"".
     | | :  `- \\`.;`\\ _ /`;.`/ - ` : | |
     \\  \\ `-.   \\_ __\\ /__ _/   .-` /  /
======`-.____`-.___\\_____/___.-`____.-'======
                   `=---='
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
         pass System Test!
*/


Error: 0

Fixed submission:

#include <bits/stdc++.h>

using namespace std;

#define REP1(i, n) for (int i = 1, i##_len = (n); i < i##_len; ++i)
#define REP(i, n) for (int i = 0, i##_len = (n); i < i##_len; ++i)
#define pow(x) x *x
#define ll long long
static const ll MAX = 1000000;
static const ll INFTY = 1e12;
static const ll MOD = 1000000007;

template <typename T> inline string toString(const T &a) {
  ostringstream oss;
  oss << a;
  return oss.str();
};

struct edge {
  ll to, cost;
};

using Graph = vector<vector<int>>;
using _Graph = vector<vector<edge>>;

const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, 1, 0, -1};

// 深さ優先探索
vector<bool> seen;
vector<int> colors;

// int H, W, N;
int sx, sy, gx, gy;
vector<vector<char>> field;
vector<vector<int>> dist;
// vector<pair<int, int>> gx, gy;
deque<pair<int, int>> que;

typedef vector<vector<int>> Matrix;

const int INF = 100000000;

int main() {

  int N, K;
  cin >> N >> K;
  vector<int> d(K);
  vector<vector<int>> A(K);
  vector<bool> su(N, false);
  REP(i, K) {
    cin >> d[i];
    REP(j, d[i]) {
      int a;
      cin >> a;
      a--;
      A[j].push_back(a);
      su[a] = true;
    }
  }
  int count = 0;
  REP(i, N) {
    if (su[i] == false) {
      count++;
    }
  }

  cout << count << endl;
}

/*
                   _ooOoo_
                  o8888888o
                  88" . "88
                  (| -_- |)
                  O\\  =  /O
               ____/`---'\\____
             .'  \\\\|     |//  `.
            /  \\\\|||  :  |||//  \\
           /  _||||| -:- |||||-  \\
           |   | \\\\\\  -  /// |   |
           | \\_|  ''\\---/''  |   |
           \\  .-\\__  `-`  ___/-. /
         ___`. .'  /--.--\\  `. . __
      ."" '<  `.___\\_<|>_/___.'  >'"".
     | | :  `- \\`.;`\\ _ /`;.`/ - ` : | |
     \\  \\ `-.   \\_ __\\ /__ _/   .-` /  /
======`-.____`-.___\\_____/___.-`____.-'======
                   `=---='
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
         pass System Test!
*/