Language: C++

#include <bits/stdc++.h>
#include <tr1/unordered_map>
#define ri register int
#define ptf printf
using namespace std;
typedef double db;
typedef long double ld;
typedef long long ll;
typedef vector <int> poly;
typedef pair <int, int> pii;
typedef pair <ll, int> pli;
typedef pair <int, ll> pil;
typedef pair <ll, ll> pll;
typedef unsigned long long ulll;
typedef unsigned int uii;
typedef string strr;
#define fi first
#define se second
#define pb push_back
#define ppp pop_back
#define rez resize
const ll Inf = 2e18;
const int rlen = 1 << 20, inf = 0x3f3f3f3f;
char buf[rlen], *ib = buf, *ob = buf;
#define gc() getchar()//(((ib == ob) && (ob = (ib =  buf) + fread(buf, 1, rlen, stdin)), ib == ob) ? -1 : *ib++)
inline int read() {
  static int ans, f;
  static char ch;
  ans = 0, ch = gc(), f = 1;
  while (!isdigit(ch)) f ^= ch == '-', ch = gc();
  while (isdigit(ch)) ans = (ans << 3) + (ans << 1) + (ch ^ 48), ch = gc();
  return f ? ans: -ans;
}
inline ll readl() {
  static ll ans;
  static char ch;
  for (ans = 0, ch = gc(); !isdigit(ch); ch = gc());
  while (isdigit(ch)) ans = ((ans << 2) + ans << 1) + (ch ^ 48), ch = gc();
  return ans;
}
inline int Read(char *s) {
  static int top;
  static char ch;
  top = 0, ch = gc();
  while (!isalpha(ch) && !isdigit(ch)) ch = gc();
  while (isalpha(ch) || isdigit(ch)) s[++top] = ch, ch = gc();
  return top;
}
namespace modular {
  const int mod = 998244353;//= 1e9 + 7;
  //int mod;
  int ret;
  inline int add(int a, int b) { return a + b < mod ? a + b : a + b - mod; }
  inline int dec(int a, int b) { return a < b ? a - b + mod : a - b; }
  inline int mul(int a, int b) { return (ll) a * b % mod; }
  inline void Add(int &a, int b) { a = a + b < mod ? a + b : a + b - mod; }
  inline void Dec(int &a, int b) { a = a < b? a - b + mod : a - b; }
  inline void Mul(int &a, int b) { a = (ll) a * b % mod; }
  inline int ksm(int a, int p) {
    for (ret = 1; p; p >>= 1, Mul(a, a)) (p & 1) && (Mul(ret, a), 1);
    return ret;
  }
  inline int Inv(int a) { return ksm(a, mod - 2); }
  inline int sqr(int a) { return (ll) a * a % mod; }
  inline int cub(int a) { return (ll) a * a % mod * a % mod; }
} using namespace modular;
template <typename T> inline void ckmax(T &a, T b) { a < b ? a = b : 0; }
template <typename T> inline void ckmin(T &a, T b) { a > b ? a = b : 0; }
template <typename T> inline T Abs(T a) { return a < 0 ? -a : a; }
template <typename T> inline T gcd(T a, T b) {
  T t;
  while (b) t = a, a = b, b = t - t / a * a;
  return a;
}
template <typename T> inline void exgcd(T a, T b, T &x, T &y) {
  if (!b) {
    x = 1, y = 0;
    return;
  }
  exgcd(b, a - a / b * b, y, x);
  y -= a / b * x;
}
const int N = 1e6 + 5;
int n, m, K, d[N], x1, x2, y1, y2;
int L[N], R[N], U[N], D[N];
char S[N];
bool s[N];
pii a[N];
map <pii, int> idx;
int main() {
  #ifdef ldxcaicai
  freopen("lx.in", "r", stdin);
  #endif
  scanf("%d%d%d", &n, &m, &K);
  scanf("%d%d%d%d", &x1, &y1, &x2, &y2);
  int tot = 0;
  for (ri i = 1; i <= n; ++i) for (ri j = 1; j <= m; ++j) idx[pii(i, j)] = ++tot;
  tot = 0;
  for (ri i = 1; i <= n; ++i) {
    scanf("%s", S + 1);
    for (ri j = 1; j <= m; ++j) {
      s[++tot] = S[j] == '.';
      if (i > 1) {
        U[idx[pii(i, j)]] = idx[pii(i - 1, j)];
      }
      if (i < n) {
        D[idx[pii(i, j)]] = idx[pii(i + 1, j)];
      }
      if (j > 1) {
        L[idx[pii(i, j)]] = idx[pii(i, j - 1)];
      }
      if (j < m) {
        R[idx[pii(i, j)]] = idx[pii(i, j + 1)];
      }
    }
  }
  queue <int> q;
  q.push(idx[pii(x1, y1)]);
  while (q.size()) {
    int x = q.front();
    q.pop();
    if (idx[pii(x2, y2)] == x) return cout << d[x], 0;
    int ct = 1;
    vector <int> tmp;
    for (ri i = U[x]; i; i = U[i]) {
      if (!s[i] || ct > K) break;
      U[x] = U[i];
      tmp.pb(i);
      ++ct;
      d[i] = d[x] + 1;
      L[R[i]] = L[i], R[L[i]] = R[i];
      q.push(i);
    }
    while (tmp.size()) U[tmp.back()] = U[x], D[tmp.back()] = D[x], tmp.ppp();
    ct = 1;
    for (ri i = D[x]; i; i = D[i]) {
      if (!s[i] || ct > K) break;
      D[x] = D[i];
      tmp.pb(i);
      ++ct;
      d[i] = d[x] + 1;
      L[R[i]] = L[i], R[L[i]] = R[i];
      q.push(i);
    }
    while (tmp.size()) U[tmp.back()] = U[x], D[tmp.back()] = D[x], tmp.ppp();
    ct = 1;
    for (ri i = L[x]; i; i = L[i]) {
      if (!s[i] || ct > K) break;
      L[x] = L[i];
      tmp.pb(i);
      ++ct;
      d[i] = d[x] + 1;
      U[D[i]] = U[i], D[U[i]] = D[i];
      q.push(i);
    }
    while (tmp.size()) L[tmp.back()] = L[x], R[tmp.back()] = R[x], tmp.ppp();
    ct = 1;
    for (ri i = R[x]; i; i = R[i]) {
      if (!s[i] || ct > K) break;
      R[x] = R[i];
      tmp.pb(i);
      ++ct;
      d[i] = d[x] + 1;
      U[D[i]] = U[i], D[U[i]] = D[i];
      q.push(i);
    }
    while (tmp.size()) L[tmp.back()] = L[x], R[tmp.back()] = R[x], tmp.ppp();
  }
  cout << -1;
  return 0;
}

Compiler output:
a.cc:84:28: error: 'int y1' redeclared as different kind of entity
   84 | int n, m, K, d[N], x1, x2, y1, y2;
      |                            ^~
In file included from /usr/include/features.h:523,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/os_defines.h:39,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/c++config.h:683,
                 from /usr/include/c++/14/cassert:43,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:33,
                 from a.cc:1:
/usr/include/x86_64-linux-gnu/bits/mathcalls.h:257:1: note: previous declaration 'double y1(double)'
  257 | __MATHCALL (y1,, (_Mdouble_));
      | ^~~~~~~~~~
a.cc: In function 'int main()':
a.cc:97:11: warning: ISO C++17 does not allow 'register' storage class specifier [-Wregister]
   97 |   for (ri i = 1; i <= n; ++i) for (ri j = 1; j <= m; ++j) idx[pii(i, j)] = ++tot;
      |           ^
a.cc:97:39: warning: ISO C++17 does not allow 'register' storage class specifier [-Wregister]
   97 |   for (ri i = 1; i <= n; ++i) for (ri j = 1; j <= m; ++j) idx[pii(i, j)] = ++tot;
      |                                       ^
a.cc:99:11: warning: ISO C++17 does not allow 'register' storage class specifier [-Wregister]
   99 |   for (ri i = 1; i <= n; ++i) {
      |           ^
a.cc:101:13: warning: ISO C++17 does not allow 'register' storage class specifier [-Wregister]
  101 |     for (ri j = 1; j <= m; ++j) {
      |             ^
a.cc:118:24: error: no matching function for call to 'std::pair<int, int>::pair(int&, double (&)(double) noexcept)'
  118 |   q.push(idx[pii(x1, y1)]);
      |                        ^
In file included from /usr/include/c++/14/bits/stl_algobase.h:64,
                 from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51:
/usr/include/c++/14/bits/stl_pair.h:913:28: note: candidate: 'template<class _U1, class _U2, typename std::enable_if<(std::_PCC<((! std::is_same<int, _U1>::value) || (! std::is_same<int, _U2>::value)), int, int>::_MoveConstructiblePair<_U1, _U2>() && (! std::_PCC<((! std::is_same<int, _U1>::value) || (! std::is_same<int, _U2>::value)), int, int>::_ImplicitlyMoveConvertiblePair<_U1, _U2>())), bool>::type <anonymous> > constexpr std::pair<_T1, _T2>::pair(std::pair<_U1, _U2>&&) [with _U2 = _U1; typename std::enable_if<(std::_PCC<((! std::is_same<_T1, _U1>::value) || (! std::is_same<_T2, _U2>::value)), _T1, _T2>::_MoveConstructiblePair<_U1, _U2>() && (! std::_PCC<((! std::is_same<_T1, _U1>::value) || (! std::is_same<_T2, _U2>::value)), _T1, _T2>::_ImplicitlyMoveConvertiblePair<_U1, _U2>())), bool>::type <anonymous> = _U2; _T1 = int; _T2 = int]'
  913 |         explicit constexpr pair(pair<_U1, _U2>&& __p)
      |                            ^~~~
/usr/include/c++/14/bits/stl_pair.h:913:28: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_pair.h:902:19: note: candidate: 'template<class _U1, class _U2, typename std::enable_if<(std::_PCC<((! std::is_same<int, _U1>::value) || (! std::is_same<int, _U2>::value)), int, int>::_MoveConstructiblePair<_U1, _U2>() && std::_PCC<((! std::is_same<int, _U1>::value) || (! std::is_same<int, _U2>::value)), int, int>::_ImplicitlyMoveConvertiblePair<_U1, _U2>()), bool>::type <anonymous> > constexpr std::pair<_T1, _T2>::pair(std::pair<_U1, _U2>&&) [with _U2 = _U1; typename std::enable_if<(std::_PCC<((! std::is_same<_T1, _U1>::value) || (! std::is_same<_T2, _U2>::value)), _T1, _T2>::_MoveConstructiblePair<_U1, _U2>() && std::_PCC<((! std::is_same<_T1, _U1>::value) || (! std::is_same<_T2, _U2>::value)), _T1, _T2>::_ImplicitlyMoveConvertiblePair<_U1, _U2>()), bool>::type <anonymous> = _U2; _T1 = int; _T2 = int]'
  902 |         constexpr pair(pair<_U1, _U2>&& __p)
      |                   ^~~~
/usr/include/c++/14/bits/stl_pair.h:902:19: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_pair.h:891:28: note: candidate: 'template<class _U1, class _U2, typename std::enable_if<(_MoveConstructiblePair<_U1, _U2>() && (! _ImplicitlyMoveConvertiblePair<_U1, _U2>())), bool>::type <anonymous> > constexpr std::pair<_T1, _T2>::pair(_U1&&, _U2&&) [with _U2 = _U1; typename std::enable_if<(std::_PCC<true, _T1, _T2>::_MoveConstructiblePair<_U1, _U2>() && (! std::_PCC<true, _T1, _T2>::_ImplicitlyMoveConvertiblePair<_U1, _U2>())), bool>::type <anonymous> = _U2; _T1 = int; _T2 = int]'
  891 |         explicit constexpr pair(_U1&& __x, _U2&& __y)
      |                            ^~~~
/usr/include/c++/14/bits/stl_pair.h:891:28: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_pair.h:890:38: error: no type named 'type' in 'struct std::enable_if<false, bool>'
  890 |                          bool>::type=false>
      |                                      ^~~~~
/usr/include/c++/14/bits/stl_pair.h:881:19: note: candidate: 'template<class _U1, class _U2, typename std::enable_if<(_MoveConstructiblePair<_U1, _U2>() && _ImplicitlyMoveConvertiblePair<_U1, _U2>()), bool>::type <anonymous> > constexpr std::pair<_T1, _T2>::pair(_U1&&, _U2&&) [with _U2 = _U1; typename std::enable_if<(std::_PCC<true, _T1, _T2>::_MoveConstructiblePair<_U1, _U2>() && std::_PCC<true, _T1, _T2>::_ImplicitlyMoveConvertiblePair<_U1, _U2>()), bool>::type <anonymous> = _U2; _T1 = int; _T2 = int]'
  881 |         constexpr pair(_U1&& __x, _U2&& __y)
      |                   ^~~~
/usr/include/c++/14/bits/stl_pair.h:881:19: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_pair.h:880:38: error: no type named 'type' in 'struct std::enable_if<false, bool>'
  880 |                          bool>::type=true>
      |                                      ^~~~
/usr/include/c++/14/bits/stl_pair.h:869:9: note: candidate: 'template<class _U2, typename std::enable_if<std::__and_<std::is_pointer<int>, std::__not_<std::is_reference<_Tp> >, std::is_constructible<int, _U2>, std::__not_<std::is_constructible<int, const _U1&> >, std::__not_<std::is_convertible<_U2, int> > >::value, bool>::type <anonymous> > constexpr std::pair<_T1, _T2>::pair(__zero_as_null_pointer_constant, _U2&&, ...) [with typename std::enable_if<std::__and_<std::is_pointer<_Tp>, std::__not_<std::is_reference<_U1> >, std::is_constructible<_T2, _U2>, std::__not_<std::is_constructible<_T1, const _U1&> >, std::__not_<std::is_convertible<_U2, _T2> > >::value, bool>::type <anonymous> = _U2; _T1 = int; _T2 = int]'
  869 |         pair(__zero_as_null_pointer_constant, _U2&& __y, ...)
      |         ^~~~
/usr/include/c++/14/bits/stl_pair.h:869:9: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_pair.h:866:38: error: no type named 'type' in 'struct std::enable_if<false, bool>'
  866 |                              bool> = false>
      |                                      ^~~~~
/usr/include/c++/14/bits/stl_pair.h:856:9: note: candidate: 'template<class _U2, typename std::enable_if<std::__and_<std::is_pointer<int>, std::__not_<std::is_reference<_Tp> >, std::is_constructible<int, _U2>, std::__not_<std::is_constructible<int, const _U1&> >, std::is_convertible<_U2, int> >::value, bool>::type <anonymous> > constexpr std::pair<_T1, _T2>::pair(__zero_as_null_pointer_constant, _U2&&, ...) [with typename std::enable_if<std::__and_<std::is_pointer<_Tp>, std::__not_<std::is_reference<_U1> >, std::is_constructible<_T2, _U2>, std::__not_<std::is_constructible<_T1, const _U1&> >, std::is_convertible<_U2, _T2> >::value, bool>::type <anonymous> = _U2; _T1 = int; _T2 = int]'
  856 |         pair(__zero_as_null_pointer_constant, _U2&& __y, ...)
      |         ^~~~
/usr/include/c++/14/bits/stl_pair.h:856:9: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_pair.h:853:38: error: no type named 'type' in 'struct std::enable_if<false, bool>'
  853 |                              bool> = true>
      |                                      ^~~~
/usr/include/c++/14/bits/stl_pair.h:843:9: note: candidate: 'template<class _U1, typename std::enable_if<std::__and_<std::__not_<std::is_reference<_Tp> >, std::is_pointer<int>, std::is_constructible<int, _U2>, std::__not_<std::is_constructible<int, const _U1&> >, std::__not_<std::is_convertible<_U2, int> > >::value, bool>::type <anonymous> > constexpr std::pair<_T1, _T2>::pair(_U1&&, __zero_as_null_pointer_constant, ...) [with typename std::enable_if<std::__and_<std::__not_<std::is_reference<_U1> >, std::is_pointer<_T2>, std::is_constructible<_T1, _U1>, std::__not_<std::is_constructible<_T1, const _U1&> >, std::__not_<std::is_convertible<_U1, _T1> > >::value, bool>::type <anonymous> = _U1; _T1 = int; _T2 = int]'
  843 |         pair(_U1&& __x, __zero_as_null_pointer_constant, ...)
      |         ^~~~
/usr/include/c++/14/bits/stl_pair.h:843:9: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_pair.h:840:38: error: no type named 'type' in 'struct std::enable_if<false, bool>'
  840 |                              bool> = false>
      |                                      ^~~~~
/usr/include/c++/14/bits/stl_pair.h:830:9: note: candidate: 'template<class _U1, typename std::enable_if<std::__and_<std::__not_<std::is_reference<_Tp> >, std::is_pointer<int>, std::is_constructible<int, _U2>, std::__not_<std::is_constructible<int, const _U1&> >, std::is_convertible<_U2, int> >::value, bool>::type <anonymous> > constexpr std::pair<_T1, _T2>::pair(_U1&&, __zero_as_null_pointer_constant, ...) [with typename std::enable_if<std::__and_<std::__not_<std::is_reference<_U1> >, std::is_pointer<_T2>, std::is_constructible<_T1, _U1>, std::__not_<std::is_constructible<_T1, const _U1&> >, std::is_convertible<_U1, _T1> >::value, bool>::type <anonymous> = _U1; _T1 = int; _T2 = int]'
  830 |         pair(_U1&& __x, __zero_as_null_pointer_constant, ...)
      |         ^~~~
/usr/include/c++/14/bits/stl_pair.h:830:9: note:   template argument deduction/substitution failed:
/usr/include/c++/14/bits/stl_pair.h:827:38: error: no type named 'type' in 'struct std::enable_if<false, bool>'
  827 |                              bool> = true>
      |                                      ^~~~
/usr/include/c++/14/bits/stl_