Language: C++

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

// hamko utils
#define rep(i,n) for(long long i = 0; i < static_cast<long long>(n); i++)
#define repi(i,a,b) for(long long i = static_cast<long long>(a); i < static_cast<long long>(b); i++)
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define fi first
#define se second
#define mt make_tuple
#define mp make_pair
template<class T1, class T2> bool chmin(T1 &a, T2 b) { return b < a && (a = b, true); }
template<class T1, class T2> bool chmax(T1 &a, T2 b) { return a < b && (a = b, true); }

using ll = long long; using vll = vector<ll>; using vvll = vector<vll>; using P = pair<ll, ll>;
using ld = long double;  using vld = vector<ld>; 
using vi = vector<int>; using vvi = vector<vi>; vll conv(vi& v) { vll r(v.size()); rep(i, v.size()) r[i] = v[i]; return r; }

inline void input(int &v){ v=0;char c=0;int p=1; while(c<'0' || c>'9'){if(c=='-')p=-1;c=getchar();} while(c>='0' && c<='9'){v=(v<<3)+(v<<1)+c-'0';c=getchar();} v*=p; } // これを使うならば、tieとかを消して！！
template <typename T, typename U> ostream &operator<<(ostream &o, const pair<T, U> &v) {  o << "(" << v.first << ", " << v.second << ")"; return o; }
template<size_t...> struct seq{}; template<size_t N, size_t... Is> struct gen_seq : gen_seq<N-1, N-1, Is...>{}; template<size_t... Is> struct gen_seq<0, Is...> : seq<Is...>{};
template<class Ch, class Tr, class Tuple, size_t... Is>
void print_tuple(basic_ostream<Ch,Tr>& os, Tuple const& t, seq<Is...>){ using s = int[]; (void)s{0, (void(os << (Is == 0? "" : ", ") << get<Is>(t)), 0)...}; }
template<class Ch, class Tr, class... Args> 
auto operator<<(basic_ostream<Ch, Tr>& os, tuple<Args...> const& t) -> basic_ostream<Ch, Tr>& { os << "("; print_tuple(os, t, gen_seq<sizeof...(Args)>()); return os << ")"; }
ostream &operator<<(ostream &o, const vvll &v) { rep(i, v.size()) { rep(j, v[i].size()) o << v[i][j] << " "; o << endl; } return o; }
template <typename T> ostream &operator<<(ostream &o, const vector<T> &v) { o << '['; rep(i, v.size()) o << v[i] << (i != v.size()-1 ? ", " : ""); o << "]";  return o; }
template <typename T> ostream &operator<<(ostream &o, const deque<T> &v) { o << '['; rep(i, v.size()) o << v[i] << (i != v.size()-1 ? ", " : ""); o << "]";  return o; }
template <typename T>  ostream &operator<<(ostream &o, const set<T> &m) { o << '['; for (auto it = m.begin(); it != m.end(); it++) o << *it << (next(it) != m.end() ? ", " : ""); o << "]";  return o; }
template <typename T>  ostream &operator<<(ostream &o, const unordered_set<T> &m) { o << '['; for (auto it = m.begin(); it != m.end(); it++) o << *it << (next(it) != m.end() ? ", " : ""); o << "]";  return o; }
template <typename T, typename U>  ostream &operator<<(ostream &o, const map<T, U> &m) { o << '['; for (auto it = m.begin(); it != m.end(); it++) o << *it << (next(it) != m.end() ? ", " : ""); o << "]";  return o; }
template <typename T, typename U, typename V>  ostream &operator<<(ostream &o, const unordered_map<T, U, V> &m) { o << '['; for (auto it = m.begin(); it != m.end(); it++) o << *it; o << "]";  return o; }
vector<int> range(const int x, const int y) { vector<int> v(y - x + 1); iota(v.begin(), v.end(), x); return v; }
template <typename T> istream& operator>>(istream& i, vector<T>& o) { rep(j, o.size()) i >> o[j]; return i;}
template <typename T, typename S, typename U> ostream &operator<<(ostream &o, const priority_queue<T, S, U> &v) { auto tmp = v; while (tmp.size()) { auto x = tmp.top(); tmp.pop(); o << x << " ";} return o; }
template <typename T> ostream &operator<<(ostream &o, const queue<T> &v) { auto tmp = v; while (tmp.size()) { auto x = tmp.front(); tmp.pop(); o << x << " ";} return o; }
template <typename T> ostream &operator<<(ostream &o, const stack<T> &v) { auto tmp = v; while (tmp.size()) { auto x = tmp.top(); tmp.pop(); o << x << " ";} return o; }
template <typename T> unordered_map<T, ll> counter(vector<T> vec){unordered_map<T, ll> ret; for (auto&& x : vec) ret[x]++; return ret;};
string substr(string s, P x) {return s.substr(x.fi, x.se - x.fi); }
void vizGraph(vvll& g, int mode = 0, string filename = "out.png") { ofstream ofs("./out.dot"); ofs << "digraph graph_name {" << endl; set<P> memo; rep(i, g.size())  rep(j, g[i].size()) { if (mode && (memo.count(P(i, g[i][j])) || memo.count(P(g[i][j], i)))) continue; memo.insert(P(i, g[i][j])); ofs << "    " << i << " -> " << g[i][j] << (mode ? " [arrowhead = none]" : "")<< endl;  } ofs << "}" << endl; ofs.close(); system((string("dot -T png out.dot >") + filename).c_str()); }
class ScopedTime {
public:
    ScopedTime(const std::string& msg = "") : msg_(msg) {
        start_ = std::chrono::system_clock::now();
    }
    void lap(const std::string& msg) {
        const auto duration_time = std::chrono::system_clock::now() - start_;
        const auto duration_ms = std::chrono::duration_cast<std::chrono::milliseconds>(duration_time);
        std::cerr << "[" << duration_ms.count() << " ms] " << msg << std::endl;
    }
    virtual ~ScopedTime() {
        this->lap(msg_);
    }
private:
    std::chrono::system_clock::time_point start_;
    std::string msg_;
};

size_t g_random_seed;
struct init_{ init_(){ std::ios::sync_with_stdio(false); std::cin.tie(0); srand(static_cast<unsigned int>(time(NULL))); g_random_seed = RAND_MAX / 2 + rand() / 2; } } init__;
namespace std { using argument_type = P; template<> struct hash<argument_type> { size_t operator()(argument_type const& x) const { size_t seed = g_random_seed; seed ^= hash<ll>{}(x.fi); seed ^= (hash<ll>{}(x.se) << 1); return seed; } }; }; // hash for various class

#define ldout fixed << setprecision(40) 
#define EPS (double)1e-14
#define INF (ll)1e18
#define mo  (ll)(1e9+7)
// end of hamko utils
template <typename T, typename X> auto vectors(T a, X x) { return vector<T>(x, a); }
template <typename T, typename X, typename Y, typename... Zs> auto vectors(T a, X x, Y y, Zs... zs) { auto cont = vectors(a, y, zs...); return vector<decltype(cont)>(x, cont); }
// usage: vector<vector<vector<double> > > dp = vectors(double(), 10, 20, 30);

int N;
ll K;

vector<vector<ll>> multiply_matrix(vector<vector<ll> >& a, vector<vector<ll> >& b) {
    vector<vector<ll> > c = vectors(ll(), N, N);
    for (int i = 0; i < N; i++) {
        for (int j = 0; j < N; j++) {
            for (int k = 0; k < N; k++) {
                c[i][j] += a[i][k] * b[k][j];
                c[i][j]%=mo;
            }
        }
    }
    return std::move(c);
}

vector<vector<ll>> power_matrix(vector<vector<ll> >& a, ll n) {
    vector<vector<ll> > b = vectors(ll(), N, N);
    if (n == 0) {
        for (int i = 0; i < N; i++) {
            b[i][i] = 1;
        }
        return std::move(b);
    }
    if (n == 1) {
        return a;
    }
    ll x = n/2;
    ll y = n%2;
    if (x == 0) {
        return a;
    }
    //std::cout << x << " " << y << std::endl;
    b = power_matrix(a, x);
    b = multiply_matrix(b, b);
    if (y) {
        b = multiply_matrix(b, a);
    }
    return std::move(b);
}

int main(void) {
    cin >> N >> K;
    vector<vector<ll> > a = vectors(ll(), N, N);
    for (int i = 0; i < N; i++) {
        for (int j = 0; j < N; j++) {
            int k;
            cin >> k;
            a[i][j] = k;
        }
    }
    //std::cout << a << std::endl;
    auto b = power_matrix(a, K);
    //std::cout << b << std::endl;
    ll ones = 0;
    for (int i = 0; i < N; i++) {
        for (int j = 0; j < N; j++) {
            ones += b[i][j];
            ones%=mo;
        }
    }
    std::cout << ones << std::endl;


    return 0;
}


Compiler output:
a.cc:1:1: error: extended character √ is not valid in an identifier
    1 | √#include <bits/stdc++.h>
      | ^
a.cc:1:2: error: stray '#' in program
    1 | √#include <bits/stdc++.h>
      |  ^
a.cc:1:1: error: '\U0000221a' does not name a type
    1 | √#include <bits/stdc++.h>
      | ^
a.cc:17:35: error: 'vector' does not name a type
   17 | using ll = long long; using vll = vector<ll>; using vvll = vector<vll>; using P = pair<ll, ll>;
      |                                   ^~~~~~
a.cc:17:60: error: 'vector' does not name a type
   17 | using ll = long long; using vll = vector<ll>; using vvll = vector<vll>; using P = pair<ll, ll>;
      |                                                            ^~~~~~
a.cc:17:83: error: 'pair' does not name a type
   17 | using ll = long long; using vll = vector<ll>; using vvll = vector<vll>; using P = pair<ll, ll>;
      |                                                                                   ^~~~
a.cc:18:38: error: 'vector' does not name a type
   18 | using ld = long double;  using vld = vector<ld>;
      |                                      ^~~~~~
a.cc:19:12: error: 'vector' does not name a type
   19 | using vi = vector<int>; using vvi = vector<vi>; vll conv(vi& v) { vll r(v.size()); rep(i, v.size()) r[i] = v[i]; return r; }
      |            ^~~~~~
a.cc:19:37: error: 'vector' does not name a type
   19 | using vi = vector<int>; using vvi = vector<vi>; vll conv(vi& v) { vll r(v.size()); rep(i, v.size()) r[i] = v[i]; return r; }
      |                                     ^~~~~~
a.cc:19:49: error: 'vll' does not name a type; did you mean 'll'?
   19 | using vi = vector<int>; using vvi = vector<vi>; vll conv(vi& v) { vll r(v.size()); rep(i, v.size()) r[i] = v[i]; return r; }
      |                                                 ^~~
      |                                                 ll
a.cc: In function 'void input(int&)':
a.cc:21:89: error: 'getchar' was not declared in this scope
   21 | inline void input(int &v){ v=0;char c=0;int p=1; while(c<'0' || c>'9'){if(c=='-')p=-1;c=getchar();} while(c>='0' && c<='9'){v=(v<<3)+(v<<1)+c-'0';c=getchar();} v*=p; } // これを使うならば、tieとかを消して！！
      |                                                                                         ^~~~~~~
a.cc:3:1: note: 'getchar' is defined in header '<cstdio>'; this is probably fixable by adding '#include <cstdio>'
    2 | #include <sys/time.h>
  +++ |+#include <cstdio>
    3 | using namespace std;
a.cc:21:149: error: 'getchar' was not declared in this scope
   21 | inline void input(int &v){ v=0;char c=0;int p=1; while(c<'0' || c>'9'){if(c=='-')p=-1;c=getchar();} while(c>='0' && c<='9'){v=(v<<3)+(v<<1)+c-'0';c=getchar();} v*=p; } // これを使うならば、tieとかを消して！！
      |                                                                                                                                                     ^~~~~~~
a.cc:21:149: note: 'getchar' is defined in header '<cstdio>'; this is probably fixable by adding '#include <cstdio>'
a.cc: At global scope:
a.cc:22:35: error: 'ostream' does not name a type
   22 | template <typename T, typename U> ostream &operator<<(ostream &o, const pair<T, U> &v) {  o << "(" << v.first << ", " << v.second << ")"; return o; }
      |                                   ^~~~~~~
a.cc:23:10: error: 'size_t' has not been declared
   23 | template<size_t...> struct seq{}; template<size_t N, size_t... Is> struct gen_seq : gen_seq<N-1, N-1, Is...>{}; template<size_t... Is> struct gen_seq<0, Is...> : seq<Is...>{};
      |          ^~~~~~
a.cc:23:44: error: 'size_t' has not been declared
   23 | template<size_t...> struct seq{}; template<size_t N, size_t... Is> struct gen_seq : gen_seq<N-1, N-1, Is...>{}; template<size_t... Is> struct gen_seq<0, Is...> : seq<Is...>{};
      |                                            ^~~~~~
a.cc:23:54: error: 'size_t' has not been declared
   23 | template<size_t...> struct seq{}; template<size_t N, size_t... Is> struct gen_seq : gen_seq<N-1, N-1, Is...>{}; template<size_t... Is> struct gen_seq<0, Is...> : seq<Is...>{};
      |                                                      ^~~~~~
a.cc:23:93: error: 'N' was not declared in this scope
   23 | template<size_t...> struct seq{}; template<size_t N, size_t... Is> struct gen_seq : gen_seq<N-1, N-1, Is...>{}; template<size_t... Is> struct gen_seq<0, Is...> : seq<Is...>{};
      |                                                                                             ^
a.cc:23:98: error: 'N' was not declared in this scope
   23 | template<size_t...> struct seq{}; template<size_t N, size_t... Is> struct gen_seq : gen_seq<N-1, N-1, Is...>{}; template<size_t... Is> struct gen_seq<0, Is...> : seq<Is...>{};
      |                                                                                                  ^
a.cc:23:103: error: 'Is' was not declared in this scope
   23 | template<size_t...> struct seq{}; template<size_t N, size_t... Is> struct gen_seq : gen_seq<N-1, N-1, Is...>{}; template<size_t... Is> struct gen_seq<0, Is...> : seq<Is...>{};
      |                                                                                                       ^~
a.cc:23:105: error: expected parameter pack before '...'
   23 | template<size_t...> struct seq{}; template<size_t N, size_t... Is> struct gen_seq : gen_seq<N-1, N-1, Is...>{}; template<size_t... Is> struct gen_seq<0, Is...> : seq<Is...>{};
      |                                                                                                         ^~~
a.cc:23:108: error: wrong number of template arguments (3, should be at least 0)
   23 | template<size_t...> struct seq{}; template<size_t N, size_t... Is> struct gen_seq : gen_seq<N-1, N-1, Is...>{}; template<size_t... Is> struct gen_seq<0, Is...> : seq<Is...>{};
      |                                                                                                            ^
a.cc:23:75: note: provided for 'template<<declaration error>, <declaration error> > struct gen_seq'
   23 | template<size_t...> struct seq{}; template<size_t N, size_t... Is> struct gen_seq : gen_seq<N-1, N-1, Is...>{}; template<size_t... Is> struct gen_seq<0, Is...> : seq<Is...>{};
      |                                                                           ^~~~~~~
a.cc:23:122: error: 'size_t' has not been declared
   23 | template<size_t...> struct seq{}; template<size_t N, size_t... Is> struct gen_seq : gen_seq<N-1, N-1, Is...>{}; template<size_t... Is> struct gen_seq<0, Is...> : seq<Is...>{};
      |                                                                                                                          ^~~~~~
a.cc:23:154: error: 'Is' was not declared in this scope
   23 | template<size_t...> struct seq{}; template<size_t N, size_t... Is> struct gen_seq : gen_seq<N-1, N-1, Is...>{}; template<size_t... Is> struct gen_seq<0, Is...> : seq<Is...>{};
      |                                                                                                                                                          ^~
a.cc:23:156: error: expected parameter pack before '...'
   23 | template<size_t...> struct seq{}; template<size_t N, size_t... Is> struct gen_seq : gen_seq<N-1, N-1, Is...>{}; template<size_t... Is> struct gen_seq<0, Is...> : seq<Is...>{};
      |                                                                                                                                                            ^~~
a.cc:23:159: error: template argument 2 is invalid
   23 | template<size_t...> struct seq{}; template<size_t N, size_t... Is> struct gen_seq : gen_seq<N-1, N-1, Is...>{}; template<size_t... Is> struct gen_seq<0, Is...> : seq<Is...>{};
      |                                                                                                                                                               ^
a.cc:23:167: error: 'Is' was not declared in this scope
   23 | template<size_t...> struct seq{}; template<size_t N, size_t... Is> struct gen_seq : gen_seq<N-1, N-1, Is...>{}; template<size_t... Is> struct gen_seq<0, Is...> : seq<Is...>{};
      |                                                                                                                                                                       ^~
a.cc:23:169: error: expected parameter pack before '...'
   23 | template<size_t...> struct seq{}; template<size_t N, size_t... Is> struct gen_seq : gen_seq<N-1, N-1, Is...>{}; template<size_t... Is> struct gen_seq<0, Is...> : seq<Is...>{};
      |                                                                                                                                                                         ^~~
a.cc:23:172: error: template argument 1 is invalid
   23 | template<size_t...> struct seq{}; template<size_t N, size_t... Is> struct gen_seq : gen_seq<N-1, N-1, Is...>{}; template<size_t... Is> struct gen_seq<0, Is...> : seq<Is...>{};
      |                                                                                                                                                                            ^
a.cc:24:43: error: 'size_t' has not been declared
   24 | template<class Ch, class Tr, class Tuple, size_t... Is>
      |                                           ^~~~~~
a.cc:25:6: error: variable or field 'print_tuple' declared void
   25 | void print_tuple(basic_ostream<Ch,Tr>& os, Tuple const& t, seq<Is...>){ using s = int[]; (void)s{0, (void(os << (Is == 0? "" : ", ") << get<Is>(t)), 0)...}; }
      |      ^~~~~~~~~~~
a.cc:25:18: error: 'basic_ostream' was not declared in this scope
   25 | void print_tuple(basic_ostream<Ch,Tr>& os, Tuple const& t, seq<Is...>){ using s = int[]; (void)s{0, (void(os << (Is == 0? "" : ", ") << get<Is>(t)), 0)...}; }
      |                  ^~~~~~~~~~~~~
a.cc:25:34: error: expected primary-expression before ',' token
   25 | void print_tuple(basic_ostream<Ch,Tr>& os, Tuple const& t, seq<Is...>){ using s = int[]; (void)s{0, (void(os << (Is == 0? "" : ", ") << get<Is>(t)), 0)...}; }
      |                                  ^
a.cc:25:37: error: expected primary-express