source_code: import java.io.IOException;
  import java.io.InputStream;
  import java.io.PrintWriter;
  import java.math.BigInteger;
  import java.util.InputMismatchException;
  
  /**
   * @author Egor Kulikov (egor@egork.net)
   *         Created on 14.03.2010
   */
  public class TaskA implements Runnable {
  	private InputReader in;
  	private PrintWriter out;
  
  	public static void main(String[] args) {
  		new Thread(new TaskA()).start();
  //		new Template().run();
  	}
  
  	public TaskA() {
  //		String id = getClass().getName().toLowerCase();
  //		try {
  //			System.setIn(new FileInputStream(id + ".in"));
  //			System.setOut(new PrintStream(new FileOutputStream(id + ".out")));
  //		} catch (FileNotFoundException e) {
  //			throw new RuntimeException();
  //		}
  		in = new InputReader(System.in);
  		out = new PrintWriter(System.out);
  	}
  
  	public void run() {
  //        int numTests = in.readInt();
  //        for (int testNumber = 0; testNumber < numTests; testNumber++) {
  //        }
  		int n = in.readInt();
  		int[] a = new int[n];
  		for (int i = 0; i < n; i++)
  			a[i] = in.readInt();
  		boolean odd = a[0] % 2 + a[1] % 2 + a[2] % 2 >= 2;
  		for (int i = 0; i < n; i++) {
  			if (a[i] % 2 == 1 && !odd)
  				out.println(i + 1);
  			if (a[i] % 2 == 0 && odd)
  				out.println(i + 1);
  		}
  		out.close();
  	}
  
  	private static class InputReader {
  		private InputStream stream;
  		private byte[] buf = new byte[1000];
  		private int curChar, numChars;
  
  		public InputReader(InputStream stream) {
  			this.stream = stream;
  		}
  
  		private int read() {
  			if (numChars == -1)
  				throw new InputMismatchException();
  			if (curChar >= numChars) {
  				curChar = 0;
  				try {
  					numChars = stream.read(buf);
  				} catch (IOException e) {
  					throw new InputMismatchException();
  				}
  				if (numChars <= 0)
  					return -1;
  			}
  			return buf[curChar++];
  		}
  
  		public int readInt() {
  			int c = read();
  			while (isSpaceChar(c))
  				c = read();
  			int sgn = 1;
  			if (c == '-') {
  				sgn = -1;
  				c = read();
  			}
  			int res = 0;
  			do {
  				if (c < '0' || c > '9')
  					throw new InputMismatchException();
  				res *= 10;
  				res += c - '0';
  				c = read();
  			} while (!isSpaceChar(c));
  			return res * sgn;
  		}
  
  		public long readLong() {
  			int c = read();
  			while (isSpaceChar(c))
  				c = read();
  			int sgn = 1;
  			if (c == '-') {
  				sgn = -1;
  				c = read();
  			}
  			long res = 0;
  			do {
  				if (c < '0' || c > '9')
  					throw new InputMismatchException();
  				res *= 10;
  				res += c - '0';
  				c = read();
  			} while (!isSpaceChar(c));
  			return res * sgn;
  		}
  
  		public String readString() {
  			int c = read();
  			while (isSpaceChar(c))
  				c = read();
  			StringBuffer res = new StringBuffer();
  			do {
  				res.appendCodePoint(c);
  				c = read();
  			} while (!isSpaceChar(c));
  			return res.toString();
  		}
  
  		private boolean isSpaceChar(int c) {
  			return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
  		}
  
  		private String readLine0() {
  			StringBuffer buf = new StringBuffer();
  			int c = read();
  			while (c != '\n' && c != -1) {
  				buf.appendCodePoint(c);
  				c = read();
  			}
  			return buf.toString();
  		}
  
  		public String readLine() {
  			String s = readLine0();
  			while (s.trim().length() == 0)
  				s = readLine0();
  			return s;
  		}
  
  		public String readLine(boolean ignoreEmptyLines) {
  			if (ignoreEmptyLines)
  				return readLine();
  			else
  				return readLine0();
  		}
  
  		public BigInteger readBigInteger() {
  			try {
  				return new BigInteger(readString());
  			} catch (NumberFormatException e) {
  				throw new InputMismatchException();
  			}
  		}
  
  		public char readCharacter() {
  			int c = read();
  			while (isSpaceChar(c))
  				c = read();
  			return (char) c;
  		}
  
  		public double readDouble() {
  			int c = read();
  			while (isSpaceChar(c))
  				c = read();
  			int sgn = 1;
  			if (c == '-') {
  				sgn = -1;
  				c = read();
  			}
  			double res = 0;
  			while (!isSpaceChar(c) && c != '.') {
  				if (c < '0' || c > '9') {
  					if (c == 'e' || c == 'E') {
  						int e = readInt();
  						return res * Math.pow(10, e);
  					}
  					throw new InputMismatchException();
  				}
  				res *= 10;
  				res += c - '0';
  				c = read();
  			}
  			if (c == '.') {
  				c = read();
  				double m = 1;
  				while (!isSpaceChar(c)) {
  					if (c == 'e' || c == 'E') {
  						int e = readInt();
  						return res * Math.pow(10, e);
  					}
  					if (c < '0' || c > '9')
  						throw new InputMismatchException();
  					m /= 10;
  					res += (c - '0') * m;
  					c = read();
  				}
  			}
  			return res * sgn;
  		}
  	}
  }