// clang-format off
#include <bits/stdc++.h>

using namespace std;

#if __cplusplus < 201400
  #warning "Please use c++14 or higher."
  #define INLINE_V
  #define REGISTER_V register
  #define CPP14CONSTEXPR
  #define gcd __gcd
  #define CPP14ENABLE_IF
#elif __cplusplus < 201700
  #define INLINE_V
  #define REGISTER_V
  #define CPP14CONSTEXPR constexpr
  #define gcd __gcd
  #define CPP14ENABLE_IF ,enable_if_t<_is_integer<T>, int> = 0
#else
  #define INLINE_V inline
  #define REGISTER_V
  #define CPP14CONSTEXPR constexpr
  #define CPP14ENABLE_IF ,enable_if_t<_is_integer<T>, int> = 0
#endif

#if !defined(_WIN32) && !defined(LOCK_GETCHAR)
  #define getchar getchar_unlocked
#endif

#define il inline
#define mkp make_pair
#define fi first
#define se second
#define For(i,j,k) for(REGISTER_V int i=(j);i<=(k);++i) // NOLINT
#define ForDown(i,j,k) for(REGISTER_V int i=(j);i>=(k);--i) // NOLINT
#define pb push_back
#define eb emplace_back
#ifndef ONLINE_JUDGE
#define FileIO(filename) freopen(filename".in","r",stdin);freopen(filename".out","w",stdout)
#else
#define FileIO(filename)
#endif

using ll = long long;
// using lll = __int128_t;
using uint = unsigned int;
using ull = unsigned long long;
// using ulll = __uint128_t;
using db = double;
using ldb = long double;
using pii = pair<int, int>;
using pll = pair<ll, ll>;

#if __cplusplus >= 201400
  template <class T> INLINE_V constexpr bool _is_integer = numeric_limits<T>::is_integer;
  // template <> INLINE_V constexpr bool _is_integer<__int128> = true;
  // template <> INLINE_V constexpr bool _is_integer<__uint128_t> = true;
  template <> INLINE_V constexpr bool _is_integer<bool> = false;
  template <> INLINE_V constexpr bool _is_integer<char> = false;
  template <class T CPP14ENABLE_IF>
    INLINE_V constexpr T INF = numeric_limits<T>::max() >> 1;
#endif

template<typename T> constexpr il T sq(const T & x){return x*x;}
template<typename T> CPP14CONSTEXPR il void cmin(T & x, const T &y){x=min(x,y);}
template<typename T> CPP14CONSTEXPR il void cmax(T & x, const T &y){x=max(x,y);}
template<typename T> CPP14CONSTEXPR il T qpow(T x, ull y, T mod){T ans=1;x%=mod;while(y){if(y&1)(ans*=x)%=mod;(x*=x)%=mod;y>>=1;}return ans;}
template<typename T> CPP14CONSTEXPR il T qpow(T x, ull y){T ans=1;while(y){if(y&1)ans*=x;x*=x;y>>=1;}return ans;}
template<typename T CPP14ENABLE_IF> il void read(T &x){ x=0;int f=1;int c=getchar();while(!isdigit(c)){if(c=='-')f=-1;c=getchar();}while(isdigit(c)){x=x*10+c-'0';c=getchar();}x*=f;}
template<typename T, typename ... Args> il void read(T &x, Args &... y){ read(x);read(y...); }

// File head end
// clang-format on

namespace {
constexpr ll MAXN = (1 << 4) + 5;
int n, N, a[MAXN][MAXN], dx[] = {1, -1, 0, 0}, dy[] = {0, 0, 1, -1};
bitset<MAXN * MAXN> b[MAXN * MAXN];
bitset<MAXN * MAXN> ans;
#define id(x, y) (((x)-1) * N + y)

il void solve() {
  int cur = 1;
  vector<int> qwq;
  For(i, 1, N * N) {
    int row = cur;
    while (row <= N * N && !b[row][i])
      row++;
    if (row == N * N + 1)
      continue;
    swap(b[row], b[cur]);
    For(j, 1, N * N) if (j != cur) b[j] ^= b[cur];
    cur++, qwq.eb(i);
  }
  while (cur <= N * N)
    if (b[cur++][N * N + 1])
      return puts("-1"), void();
  int cnt = 0;
  for (int x : qwq)
    ans[x] = b[x][N * N + 1] ^ b[x][x], cnt += ans[x];

  cout << cnt << '\n';
  For(i, 1, N) For(j, 1, N) if (ans[id(i, j)]) cout << i - 1 << ' ' << j - 1
                                                    << '\n';
}

il void solver_main() {
  read(n), N = 1 << n;
  For(i, 1, N) For(j, 1, N) read(a[i][j]);
  For(i, 1, N) For(j, 1, N) {
    b[id(i, j)][N * N + 1] = a[i][j];
    b[id(i, j)][id(i, j)] = 1;
    For(_, 0, 3) {
      int x = i + dx[_], y = j + dy[_];
      if (!x)
        x = N;
      if (!y)
        y = N;
      if (x == N + 1)
        x = 1;
      if (y == N + 1)
        y = 1;
      b[id(i, j)][id(x, y)] = 1;
    }
  }
  solve();
}
} // namespace

signed main() { return solver_main(), 0; }