Problem p00036 (C++) — buggy submission, verdict: Runtime Error

#include <bits/stdc++.h>
using namespace std;

#define iota(i, n, b, s)                                                       \\
  for (int i = int(b); i != int((b) + (s) * (n)); i += (s))
#define range(i, n, m)                                                         \\
  iota(i, (((n) > (m)) ? ((n) - (m)) : ((m) - (n))), (n), ((n) > (m) ? -1 : 1))
#define rep(i, n) iota(i, (n), 0, 1)
#define loop for (;;)

#define INF (1e9)
#define EPS (1e-9)
#define cons(a, b) (make_pair(a, b))
#define car(a) (a.first)
#define cdr(a) (a.second)
#define cadr(a) (car(cdr(a)))
#define cddr(a) (cdr(cdr(a)))
#define all(a) a.begin(), a.end()
#define trace(var) cerr << ">>> " << #var << " = " << var << endl;

typedef long long Integer;
typedef double Real;
typedef vector<int> vi;
typedef vector<string> vs;
typedef map<string, int> Dictionary;
const Real PI = acos(-1);

template <class S, class T> ostream &operator<<(ostream &os, pair<S, T> p) {
  os << '(' << car(p) << ", " << cdr(p) << ')';
  return os;
}

template <class T> ostream &operator<<(ostream &os, vector<T> v) {
  if (v.size() == 0) {
    os << "(empty)";
    return os;
  }
  os << v[0];
  for (int i = 1, len = v.size(); i < len; ++i)
    os << ' ' << v[i];
  return os;
}

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

string fuck(vector<pair<int, int>> &xs) {
  int i0 = INF;
  int j0 = INF;
  int i1 = -INF;
  int j1 = -INF;
  bool zero = false;

  rep(k, 4) {
    int i = car(xs[k]);
    int j = cdr(xs[k]);
    i0 = min(i0, i);
    j0 = min(j0, j);
    i1 = max(i1, i);
    j1 = max(j1, j);
    if (!i && !j)
      zero = true;
  }

  if (i1 == 3)
    return "B";
  if (j1 == 3)
    return "C";
  if (i1 == 1 && j1 == 1)
    return "A";

  if (i1 == 2) {
    if (zero)
      return "F";
    return "D";
  }

  if (zero)
    return "E";
  return "G";
}

int main() {

  loop {
    string ln[8];
    rep(i, 8) cin >> ln[i];
    if (!cin)
      break;

    vector<pair<int, int>> xs;
    int mi = INF;
    int mj = INF;
    rep(i, 8) {
      rep(j, 8) {
        if (ln[i][j] == '1') {
          xs.push_back(cons(i, j));
          mi = min(mi, i);
          mj = min(mj, j);
        }
      }
    }

    rep(i, 4) { xs[i] = cons(car(xs[i]) - mi, cdr(xs[i]) - mj); }

    cout << fuck(xs) << endl;
  }

  return 0;
}

Error: WA

Fixed submission:

#include <bits/stdc++.h>
using namespace std;

#define iota(i, n, b, s)                                                       \\
  for (int i = int(b); i != int((b) + (s) * (n)); i += (s))
#define range(i, n, m)                                                         \\
  iota(i, (((n) > (m)) ? ((n) - (m)) : ((m) - (n))), (n), ((n) > (m) ? -1 : 1))
#define rep(i, n) iota(i, (n), 0, 1)
#define loop for (;;)

#define INF (1e9)
#define EPS (1e-9)
#define cons(a, b) (make_pair(a, b))
#define car(a) (a.first)
#define cdr(a) (a.second)
#define cadr(a) (car(cdr(a)))
#define cddr(a) (cdr(cdr(a)))
#define all(a) a.begin(), a.end()
#define trace(var) cerr << ">>> " << #var << " = " << var << endl;

typedef long long Integer;
typedef double Real;
typedef vector<int> vi;
typedef vector<string> vs;
typedef map<string, int> Dictionary;
const Real PI = acos(-1);

template <class S, class T> ostream &operator<<(ostream &os, pair<S, T> p) {
  os << '(' << car(p) << ", " << cdr(p) << ')';
  return os;
}

template <class T> ostream &operator<<(ostream &os, vector<T> v) {
  if (v.size() == 0) {
    os << "(empty)";
    return os;
  }
  os << v[0];
  for (int i = 1, len = v.size(); i < len; ++i)
    os << ' ' << v[i];
  return os;
}

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

string fuck(vector<pair<int, int>> &xs) {
  int i0 = INF;
  int j0 = INF;
  int i1 = -INF;
  int j1 = -INF;
  bool zero = false;

  rep(k, 4) {
    int i = car(xs[k]);
    int j = cdr(xs[k]);
    i0 = min(i0, i);
    j0 = min(j0, j);
    i1 = max(i1, i);
    j1 = max(j1, j);
    if (!i && !j)
      zero = true;
  }

  if (i1 == 3)
    return "B";
  if (j1 == 3)
    return "C";
  if (i1 == 1 && j1 == 1)
    return "A";

  if (i1 == 2) {
    if (zero)
      return "F";
    return "D";
  }

  if (zero)
    return "E";
  return "G";
}

int main() {

  loop {
    string ln[8];
    rep(i, 8) cin >> ln[i];

    vector<pair<int, int>> xs;
    int mi = INF;
    int mj = INF;
    rep(i, 8) {
      rep(j, 8) {
        if (ln[i][j] == '1') {
          xs.push_back(cons(i, j));
          mi = min(mi, i);
          mj = min(mj, j);
        }
      }
    }

    rep(i, 4) { xs[i] = cons(car(xs[i]) - mi, cdr(xs[i]) - mj); }

    cout << fuck(xs) << endl;

    getline(cin, ln[0]);
    if (!cin)
      break;
  }

  return 0;
}