Language: C

//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2,avx512f")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")
#include <iostream>
#include <iomanip>
#include <string>
#include <cmath>
#include <algorithm>
#include <vector>
#include <set>
#include <map>
#include <unordered_map>
#include <unordered_set>
#include <list>
#include <stack>
#include <queue>
#include <bitset>
#include <numeric>
#include <cassert>
#include <memory>
#include <random>
#include <functional>
#include <complex>
#include <immintrin.h>
#ifdef DEBUG
#include "./Lib/debug_VC.hpp"
#include "./Lib/Timer.hpp"
#include "./Lib/sample.hpp"
#else
#define dump(...)
#endif

/* macro */
#define FOR(i, b, e) for(ll i = (ll)(b); i < (ll)(e); ++i)
#define RFOR(i, b, e) for(ll i = (ll)(e-1); i >= (ll)(b); --i)
#define REP(i, n) FOR(i, 0, n)
#define RREP(i, n) RFOR(i, 0, n)
#define REPC(x,c) for(const auto& x:(c))
#define REPI2(it,b,e) for(auto it = (b); it != (e); ++it)
#define REPI(it,c) REPI2(it, (c).begin(), (c).end())
#define RREPI(it,c) REPI2(it, (c).rbegin(), (c).rend())
#define REPI_ERACE2(it, b, e) for(auto it = (b); it != (e);)
#define REPI_ERACE(it, c) REPI_ERACE2(it, (c).begin(), (c).end())
#define ALL(x) (x).begin(),(x).end()
#define cauto const auto&
/* macro func */
template<class T>
inline auto sort(T& t) { std::sort(ALL(t)); }
template<class T>
inline auto rsort(T& t) { std::sort((t).rbegin(), (t).rend()); }
template<class T>
inline auto unique(T& t) { (t).erase(unique((t).begin(), (t).end()), (t).end()); }
template<class T, class S>
inline auto chmax(T& t, const S& s) { if (s > t) { t = s; return true; } return false; }
template<class T, class S>
inline auto chmin(T& t, const S& s) { if (s < t) { t = s; return true; } return false; }
inline auto BR() { std::cout << "\n"; }

/* type define */
using ll = long long;
using PAIR = std::pair<ll, ll>;
using VS = std::vector<std::string>;
using VL = std::vector<long long>;
using VVL = std::vector<VL>;
using VVVL = std::vector<VVL>;
using VD = std::vector<double>;
template<class T>
using V = std::vector<T>;

/* using std */
using std::cout;
constexpr char endl = '\n';
using std::cin;
using std::pair;
using std::string;
using std::stack;
using std::queue;
using std::vector;
using std::list;
using std::map;
using std::unordered_map;
using std::multimap;
using std::unordered_multimap;
using std::set;
using std::unordered_set;
using std::unordered_multiset;
using std::multiset;
using std::bitset;
using std::priority_queue;

/* Initial processing  */
struct Preprocessing { Preprocessing() { std::cin.tie(0); std::ios::sync_with_stdio(0); }; }_Preprocessing;

/* Remove the source of the bug */
signed pow(signed, signed) { assert(false); return -1; }

/* define hash */
namespace std {
template <>	class hash<std::pair<ll, ll>> { public:	size_t operator()(const std::pair<ll, ll>& x) const { return hash<ll>()(1000000000 * x.first + x.second); } };
}

/* input */
template<class T> std::istream& operator >> (std::istream& is, vector<T>& vec) { for (T& x : vec) is >> x; return is; }

/* constant value */
constexpr ll MOD = 1000000007;
//constexpr ll MOD = 998244353;

//=============================================================================================;

signed main() {
	ll h, w, k;
	cin >> h >> w >> k;
	ll sy, sx, ey, ex;
	cin >> sy >> sx >> ey >> ex;
	--sy; --sx; --ey; --ex;
	VS mp(h);
	cin >> mp;

	// U,D,R,L
	V<V<V<PAIR>>> mnCost(h, V<V<PAIR>>(w, V<PAIR>(4, {1e7,1e7})));

	// {mn, k}, {{y, x}, way}
	using TYPE = pair<PAIR, pair<PAIR, ll>>;
	priority_queue<TYPE, vector<TYPE>, std::greater<TYPE>> q;
	auto add = [&](ll mn, ll uk, ll y, ll x, ll way) {
		if (y < 0 || x < 0 || y >= h || x >= w) { return; }
		if (mp[y][x] == '@') { return; }
		if (chmin(mnCost[y][x][way], PAIR{mn,uk})) {
			q.emplace(PAIR{mn,uk}, pair<PAIR, ll>(PAIR{y,x}, way));
		}
	};
	REP(i, 4) { add(1, 0, sy, sx, i); }
	V<PAIR> tw{{1,0},{-1,0},{0,1},{0,-1}};
	while (!q.empty()) {
		auto [mn, uk] = q.top().first;
		auto [y, x] = q.top().second.first;
		auto way = q.top().second.second;
		q.pop();
		if (mnCost[y][x][way] < PAIR{mn, uk}) { continue; }
		REP(i, 4) {
			add(mn + 1, 1, y + tw[i].first, x + tw[i].second, i);
		}
		if (uk < k) {
			add(mn, uk + 1, y + tw[way].first, x + tw[way].second, way);
		}
	}

	ll ans = 1e10;
	REPC(p, mnCost[ey][ex]) { chmin(ans, p.first); }
	cout << ((ans > 5 * 1e6) ? -1 : ans) << endl;

}




Compiler output:
main.c:5:10: fatal error: iostream: No such file or directory
    5 | #include <iostream>
      |          ^~~~~~~~~~
compilation terminated.