/* Topcoder SRM 709 D2 250-Pointer
   Robofactory
   James S. Plank
   Wed Mar  8 02:25:59 EST 2017
 */

#include <vector>
#include <iostream>
#include <cstdio>
#include <cstdlib>
using namespace std;

typedef vector <int> IVec;
typedef vector <string> SVec;

class Robofactory {
  public:
    int reveal(vector <int> query, vector <string> answer);
};

int Robofactory::reveal(vector <int> query, vector <string> answer)
{
  int i;
  int could_be_corrupted;

  /* Pass one -- if any robots give the wrong answer, return the robot. */

  for (i = 0; i < query.size(); i++) {
    if (query[i] %2 == 0 && answer[i] == "Odd") return i;
    if (query[i] %2 == 1 && answer[i] == "Even") return i;
  }

  /* Pass two -- count the number of robots who could be corrupted.  This
     means that the robot is either robot 0, or the previous robot was 
     given an odd number. */

  could_be_corrupted = 0;
  
  for (i = 0; i < query.size(); i++) {
    if (i == 0 || query[i-1]%2 == 0) could_be_corrupted++;
  }

  /* If only one robot could be corrupted, it's robot 0. */

  if (could_be_corrupted == 1) return 0;

  /* Otherwise, there are multiple robots that could be corrupted, 
     so you return -1. */

  return -1;
}