import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;

public class Main {
	public static void main(String[] args) throws IOException {
		ContestScanner scan = new ContestScanner();
		final int n = scan.nextInt();

		final int[] keyMap= new int[128];

		keyMap[(int)'A'] = 1;
		keyMap[(int)'C'] = 2;
		keyMap[(int)'G'] = 3;
		keyMap[(int)'T'] = 4;

		final Dictionary dic = new Dictionary((int)(pow(5, 12)/31)+1, (size, key) -> {
			int index = 0;

			for(int i=0, l=key.length(), multiplier = 1; i < l; i++)
			{
				index = index + keyMap[(int)key.charAt(i)] * multiplier;
				multiplier *= 5;
			}
			return index;
		});
		(new Solve(n, scan.nextObjectArray(new ICommand[n], (scanner) -> {
			String name = scanner.next();
			return name.equals("insert") ? new InsertCommand(dic, scan.next()) : name.equals("find") ? new FindCommand(dic, scan.next()) : null;
		}))).solve();
	}

	public static long pow(int a, int b)
	{
		if(b == 1) return a;

		long result = pow(a, b / 2) * pow(a, b / 2);
		if(b % 2 > 0) result *= a;

		return result;
	}
}
class Solve {
	private final int n;
	private final ICommand[] commands;

	public Solve(final int n, final ICommand[] commands)
	{
		this.n = n;
		this.commands = commands;
	}

	public void solve()
	{
		for(ICommand c: commands)
		{
			c.run();
		}
	}
}
interface ICommand {
	public void run();
}
class InsertCommand implements ICommand {
	public final int key;
	public final Dictionary dic;
	public InsertCommand(Dictionary dic, String key)
	{
		this.dic = dic;
		this.key = dic.hashCreator.hash(dic.tableSize, key);
	}
	public void run()
	{
		dic.add(key);
	}
}
class FindCommand implements ICommand {
	public final int key;
	public final Dictionary dic;
	public FindCommand(Dictionary dic, String key)
	{
		this.dic = dic;
		this.key = dic.hashCreator.hash(dic.tableSize, key);
	}
	public void run()
	{
		System.out.println((dic.find(key) ? "yes" : "no"));
	}
}
interface HashCreator {
	public int hash(int size, String value);
}
class Dictionary {
	private final int[] table;
	public final int tableSize;
	public final HashCreator hashCreator;

	public Dictionary(final int size, final HashCreator hashCreator)
	{
		this.tableSize = size;
		this.table = new int[size];
		this.hashCreator = hashCreator;
		//Arrays.fill(this.table, 0);
	}

	public void add(int key)
	{
		table[key / 31] |= (1 << (key % 31));
	}

	public boolean find(int key)
	{
		return (table[key / 31] & (1 << (key % 31))) != 0;
	}
}
class ContestScanner {
	BufferedReader reader;
	String[] line;
	int index;
	public ContestScanner() {
		reader = new BufferedReader(new InputStreamReader(System.in));
	}

	public ContestScanner(String filename) throws FileNotFoundException {
		reader = new BufferedReader(new InputStreamReader(new FileInputStream(filename)));
	}

	public static interface ICreator<T> {
		public T createFromToken(final ContestScanner scanner) throws IOException;
	}

	public static interface IArrayInitializer {
		public void initialize(final ContestScanner scanner, final int i) throws IOException;
	}

	public static interface IObjectInitializer<T> {
		public T initialValue(final ContestScanner scanner);
	}

	public static class ObjectArrayInitializer<T> implements IArrayInitializer {
		protected T[] arr;
		protected final IObjectInitializer<T> initializer;

		private ObjectArrayInitializer(T[] arr, final IObjectInitializer<T> initializer)
		{
			this.arr = arr;
			this.initializer = initializer;
		}

		public static <T> ObjectArrayInitializer<T> create(T[] arr, final IObjectInitializer<T> initializer)
		{
			return new ObjectArrayInitializer<T>(arr, initializer);
		}

		public void initialize(final ContestScanner scanner, final int i) throws IOException {
			this.arr[i] = initializer.initialValue(scanner);
		}

		public T[] getArray()
		{
			return this.arr;
		}
	}


	public static class ByteArrayInitializer implements IArrayInitializer {
		protected byte[] arr;

		private ByteArrayInitializer(final int n)
		{
			this.arr = new byte[n];
		}

		public void initialize(final ContestScanner scanner, final int i) throws IOException {
			this.arr[i] = scanner.nextByte();
		}

		public byte[] getArray()
		{
			return this.arr;
		}
	}

	public static class ShortArrayInitializer implements IArrayInitializer {
		protected short[] arr;

		private ShortArrayInitializer(final int n)
		{
			this.arr = new short[n];
		}

		public void initialize(final ContestScanner scanner, final int i) throws IOException {
			this.arr[i] = scanner.nextShort();
		}

		public short[] getArray()
		{
			return this.arr;
		}
	}

	public static class IntArrayInitializer implements IArrayInitializer {
		protected int[] arr;

		private IntArrayInitializer(final int n)
		{
			this.arr = new int[n];
		}

		public void initialize(final ContestScanner scanner, final int i) throws IOException {
			this.arr[i] = scanner.nextInt();
		}

		public int[] getArray()
		{
			return this.arr;
		}
	}

	public static class LongArrayInitializer implements IArrayInitializer {
		protected long[] arr;

		private LongArrayInitializer(final int n)
		{
			this.arr = new long[n];
		}

		public void initialize(final ContestScanner scanner, final int i) throws IOException {
			this.arr[i] = scanner.nextLong();
		}

		public long[] getArray()
		{
			return this.arr;
		}
	}

	public static class FloatArrayInitializer implements IArrayInitializer {
		protected float[] arr;

		private FloatArrayInitializer(final int n)
		{
			this.arr = new float[n];
		}

		public void initialize(final ContestScanner scanner, final int i) throws IOException {
			this.arr[i] = scanner.nextFloat();
		}

		public float[] getArray()
		{
			return this.arr;
		}
	}

	public static class DoubleArrayInitializer implements IArrayInitializer {
		protected double[] arr;

		private DoubleArrayInitializer(final int n)
		{
			this.arr = new double[n];
		}

		public void initialize(final ContestScanner scanner, final int i) throws IOException {
			this.arr[i] = scanner.nextDouble();
		}

		public double[] getArray()
		{
			return this.arr;
		}
	}

	public String nextToken() throws IOException {
		if(line == null || index >= line.length)
		{
			line = reader.readLine().trim().split(" ");
			index = 0;
		}

		return line[index++];
	}

	public String next() throws IOException {
		return nextToken();
	}

	public String readLine() throws IOException {
		line = null;
		index = 0;

		return reader.readLine();
	}

	public byte nextByte() throws IOException, NumberFormatException {
		return Byte.parseByte(nextToken());
	}

	public short nextShort() throws IOException, NumberFormatException {
		return Short.parseShort(nextToken());
	}

	public int nextInt() throws IOException, NumberFormatException {
		return Integer.parseInt(nextToken());
	}

	public long nextLong() throws IOException, NumberFormatException {
		return Long.parseLong(nextToken());
	}

	public float nextFloat() throws IOException, NumberFormatException {
		return Float.parseFloat(nextToken());
	}

	public double nextDouble() throws IOException, NumberFormatException {
		return Double.parseDouble(nextToken());
	}

	public <T> T nextObject(final ICreator<T> creator) throws IOException, NumberFormatException {
		return creator.createFromToken(this);
	}

	public int[] nextIntArray(final int N) throws IOException, NumberFormatException {
		int[] result = new int[N];

		for(int i=0; i < N; i++) result[i] = nextInt();

		return result;
	}

	public long[] nextLongArray(final int N) throws IOException, NumberFormatException {
		long[] result = new long[N];

		for(int i=0; i < N; i++) result[i] = nextLong();

		return result;
	}

	public float[] nexFloatArray(final int N) throws IOException, NumberFormatException {
		float[] result = new float[N];

		for(int i=0; i < N; i++) result[i] = nextFloat();

		return result;
	}

	public double[] nexDoubleArray(final int N) throws IOException, NumberFormatException {
		double[] result = new double[N];

		for(int i=0; i < N; i++) result[i] = nextDouble();

		return result;
	}

	public <T> T[] nextObjectArray(T[] result, final ICreator<T> creator) throws IOException, NumberFormatException {
		for(int i=0, N=result.length; i < N; i++) result[i] = nextObject(creator);

		return result;
	}

	public <T> ArrayList<T> nextGenericObjectArrayList(final int N, final ICreator<T> creator) throws IOException, NumberFormatException {
		ArrayList<T> result = new ArrayList<T>();
		for(int i=0; i < N; i++) result.add(nextObject(creator));

		return result;
	}

	public void nextTable(final int N, IArrayInitializer... arrayInitializers) throws IOException, NumberFormatException {
		for(int i=0; i < N; i++) for(IArrayInitializer initializer: arrayInitializers)
		{
			initializer.initialize(this, i);
		}
	}
}

Measured memory_bytes: 223308