#include<bits/stdc++.h>
namespace {
using namespace std;
#define rep(i,n) for(int i = 0; i < (int)(n); i++)
#define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; i--)
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)
template<class T> bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } else return false; }
template<class T> bool chmin(T& a, const T& b) { if (b < a) { a = b; return true; } else return false; }
using ll = long long;
using P = pair<int,int>;
using VI = vector<int>;
using VVI = vector<VI>;
using VL = vector<ll>;
using VVL = vector<VL>;

template<int element_size>
struct array_set {
  int state[element_size];  // -1 if not in set else index in elems
  int elems[element_size];
  int size = 0;
  array_set() { memset(state, -1, sizeof(int) * element_size); }
  void insert(int x) {
    if (state[x] == -1) {
      state[x] = size;
      elems[size] = x;
      size++;
    }
  }
  bool contains(int x) { return state[x] != -1; }
  int* begin() { return elems; }
  int* end() { return elems + size; }
  void clear() { while(size) state[elems[--size]] = -1; }
  void erase(int x) {  // not tested
    int idx = state[x];
    if (idx != -1) {
      state[x] = -1;
      size--;
      if (idx != size) {
        int y = elems[size];
        state[y] = idx;
        elems[idx] = y;
      }
    }
  }
};

constexpr int M = 75000;

array_set<M> st[17];

} int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  int n;
  cin >> n;
  VI a(n);
  rep(i, n) {
    cin >> a[i];
    rep(k, 17) if (a[i] >> k & 1) st[k].insert(i);
  }
  int g = 0;
  rrep(i, n) g ^= a[i];
  cout << int(g != 0) << endl;
  while(true) {
    if (g) {
      int msb = 31 - __builtin_clz(g);
      int i = st[msb].elems[0];
      int x = a[i], nx = x ^ g;
      a[i] = nx;
      cout << i + 1 << ' ' << x - nx << endl;
      rrep(k, msb + 1) if (g >> k & 1) {
        if (x >> k & 1) st[k].erase(i);
        else st[k].insert(i);
      }
      g = 0;
    } else {
      int i, dec;
      cin >> i >> dec;
      i--;
      int x = a[i], nx = x - dec;
      a[i] = nx;
      g = x ^ nx;
      rrep(k, 17) if (g >> k & 1) {
        if (x >> k & 1) st[k].erase(i);
        else st[k].insert(i);
      }
    }
    int ret;
    cin >> ret;
    if (ret == -1) exit(0);
  }
}