#include <iostream>
#include <vector>

using namespace std;

int main(){
  int n;cin>>n;
  vector<int> A(n);
  int nw = 0;
  for(int i = 0; n > i; i++){
    cin>>A[i];
    nw ^= A[i];
  }
  if(nw != 0){
    cout << 1 << endl;
    bool ok = false;
    for(int j = 0; !ok && n > j; j++){
      for(int k = 1; A[j] >= k; k++){
        if((nw^A[j]^(A[j]-k)) == 0){
          cout << j+1 << " " << k << endl;
          A[j] -= nw;
          ok = true;
          break;
        }
      }
    }
    int ret;cin>>ret;
    if(ret == -1)return 0;
  }else{
    cout << 0 << endl;
  }
  
  while(true){
    int i,k;cin>>i>>k;
    A[i-1] -= k;
    int ret;cin>>ret;
    if(ret == -1)return 0;
    bool ok = false;
    for(int j = 0; !ok && n > j; j++){
      for(int k = 1; A[j] >= k; k++){
        if((nw^A[j]^(A[j]-k)) == 0){
          cout << j+1 << " " << k << endl;
          A[j] -= nw;
          ok = true;
          break;
        }
      }
    }
    cin>>ret;
    if(ret == -1)return 0;
  }
}