#include <cassert>
#include <cmath>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <functional>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;

using Int = long long;

template <class T1, class T2> ostream &operator<<(ostream &os, const pair<T1, T2> &a) { return os << "(" << a.first << ", " << a.second << ")"; };
template <class T> ostream &operator<<(ostream &os, const vector<T> &as) { const int sz = as.size(); os << "["; for (int i = 0; i < sz; ++i) { if (i >= 256) { os << ", ..."; break; } if (i > 0) { os << ", "; } os << as[i]; } return os << "]"; }
template <class T> void pv(T a, T b) { for (T i = a; i != b; ++i) cerr << *i << " "; cerr << endl; }
template <class T> bool chmin(T &t, const T &f) { if (t > f) { t = f; return true; } return false; }
template <class T> bool chmax(T &t, const T &f) { if (t < f) { t = f; return true; } return false; }


int N;
vector<int> A;

int main() {
  scanf("%d", &N);
  A.resize(N);
  for (int i = 0; i < N; ++i) {
    scanf("%d", &A[i]);
  }
  
  int now = 0;
  for (int i = 0; i < N; ++i) {
    now ^= A[i];
  }
  printf("%d\n", (now != 0) ? 1 : 0);
  fflush(stdout);
  for (; ; ) {
    if (now != 0) {
      for (int i = 0; i < N; ++i) {
        if (A[i] >= (A[i] ^ now)) {
          printf("%d %d\n", i + 1, A[i] - (A[i] ^ now));
          fflush(stdout);
          A[i] ^= now;
          now = 0;
          break;
        }
      }
      int res;
      scanf("%d", &res);
      if (res == -1) exit(0);
    }
    {
      int i, k;
      scanf("%d%d", &i, &k);
      --i;
      now ^= A[i] ^ (A[i] - k);
      A[i] -= k;
      int res;
      scanf("%d", &res);
      if (res == -1) exit(0);
    }
  }
  
  return 0;
}