

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.StringTokenizer;

public class Main {

	static long expo(long base, long exp) {
		long t = 1L;
		while (exp > 0) {
			if (exp % 2 != 0)
				t = (t * base);

			base = (base * base);
			exp /= 2;
		}
		return t;
	}

	public static void main(String args[]) throws Exception {
		MyScanner sc = new MyScanner();
		PrintWriter pr = new PrintWriter(System.out);
		String a = sc.nextLine() , b = sc.nextLine();
		
		if(a.equals(b.substring(0, b.length() - 1)))
			System.out.println("Yes");
		else
			System.out.println("No");
		pr.close();
	}

	public static class MyScanner {
		BufferedReader br;
		StringTokenizer st;

		public MyScanner() {
			br = new BufferedReader(new InputStreamReader(System.in));
		}

		String next() {
			while (st == null || !st.hasMoreElements()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}

		int nextInt() {
			return Integer.parseInt(next());
		}

		long nextLong() {
			return Long.parseLong(next());
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}

		String nextLine() {
			String str = "";
			try {
				str = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return str;
		}
	}
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io import java.io.PrintWriter; PrintWriter java.io import java.util.StringTokenizer; StringTokenizer java.util public class Main {

	static long expo(long base, long exp) {
		long t = 1L;
		while (exp > 0) {
			if (exp % 2 != 0)
				t = (t * base);

			base = (base * base);
			exp /= 2;
		}
		return t;
	}

	public static void main(String args[]) throws Exception {
		MyScanner sc = new MyScanner();
		PrintWriter pr = new PrintWriter(System.out);
		String a = sc.nextLine() , b = sc.nextLine();
		
		if(a.equals(b.substring(0, b.length() - 1)))
			System.out.println("Yes");
		else
			System.out.println("No");
		pr.close();
	}

	public static class MyScanner {
		BufferedReader br;
		StringTokenizer st;

		public MyScanner() {
			br = new BufferedReader(new InputStreamReader(System.in));
		}

		String next() {
			while (st == null || !st.hasMoreElements()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}

		int nextInt() {
			return Integer.parseInt(next());
		}

		long nextLong() {
			return Long.parseLong(next());
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}

		String nextLine() {
			String str = "";
			try {
				str = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return str;
		}
	}
} Main static long expo(long base, long exp) {
		long t = 1L;
		while (exp > 0) {
			if (exp % 2 != 0)
				t = (t * base);

			base = (base * base);
			exp /= 2;
		}
		return t;
	} expo {
		long t = 1L;
		while (exp > 0) {
			if (exp % 2 != 0)
				t = (t * base);

			base = (base * base);
			exp /= 2;
		}
		return t;
	} long t = 1L; t 1L while (exp > 0) {
			if (exp % 2 != 0)
				t = (t * base);

			base = (base * base);
			exp /= 2;
		} exp > 0 exp 0 {
			if (exp % 2 != 0)
				t = (t * base);

			base = (base * base);
			exp /= 2;
		} if (exp % 2 != 0)
				t = (t * base); exp % 2 != 0 exp % 2 exp 2 0 t = (t * base) t (t * base) t base base = (base * base) base (base * base) base base exp /= 2 exp 2 return t; t long base base long exp exp public static void main(String args[]) throws Exception {
		MyScanner sc = new MyScanner();
		PrintWriter pr = new PrintWriter(System.out);
		String a = sc.nextLine() , b = sc.nextLine();
		
		if(a.equals(b.substring(0, b.length() - 1)))
			System.out.println("Yes");
		else
			System.out.println("No");
		pr.close();
	} main {
		MyScanner sc = new MyScanner();
		PrintWriter pr = new PrintWriter(System.out);
		String a = sc.nextLine() , b = sc.nextLine();
		
		if(a.equals(b.substring(0, b.length() - 1)))
			System.out.println("Yes");
		else
			System.out.println("No");
		pr.close();
	} MyScanner sc = new MyScanner(); sc new MyScanner() PrintWriter pr = new PrintWriter(System.out); pr new PrintWriter(System.out) String a = sc.nextLine() a sc.nextLine() sc.nextLine sc b = sc.nextLine(); b sc.nextLine() sc.nextLine sc if(a.equals(b.substring(0, b.length() - 1)))
			System.out.println("Yes");
		else
			System.out.println("No"); a.equals(b.substring(0, b.length() - 1)) a.equals a b.substring(0, b.length() - 1) b.substring b 0 b.length() - 1 b.length() b.length b 1 System.out.println("Yes") System.out.println System.out System System.out "Yes" System.out.println("No") System.out.println System.out System System.out "No" pr.close() pr.close pr String args[] args public static class MyScanner {
		BufferedReader br;
		StringTokenizer st;

		public MyScanner() {
			br = new BufferedReader(new InputStreamReader(System.in));
		}

		String next() {
			while (st == null || !st.hasMoreElements()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}

		int nextInt() {
			return Integer.parseInt(next());
		}

		long nextLong() {
			return Long.parseLong(next());
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}

		String nextLine() {
			String str = "";
			try {
				str = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return str;
		}
	} MyScanner BufferedReader br; br StringTokenizer st; st public MyScanner() {
			br = new BufferedReader(new InputStreamReader(System.in));
		} MyScanner {
			br = new BufferedReader(new InputStreamReader(System.in));
		} br = new BufferedReader(new InputStreamReader(System.in)) br new BufferedReader(new InputStreamReader(System.in)) String next() {
			while (st == null || !st.hasMoreElements()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return st.nextToken();
		} next {
			while (st == null || !st.hasMoreElements()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return st.nextToken();
		} while (st == null || !st.hasMoreElements()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			} st == null || !st.hasMoreElements() st == null st null !st.hasMoreElements() st.hasMoreElements() st.hasMoreElements st {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			} try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				} catch (IOException e) {
					e.printStackTrace();
				} IOException e {
					e.printStackTrace();
				} e.printStackTrace() e.printStackTrace e {
					st = new StringTokenizer(br.readLine());
				} st = new StringTokenizer(br.readLine()) st new StringTokenizer(br.readLine()) return st.nextToken(); st.nextToken() st.nextToken st int nextInt() {
			return Integer.parseInt(next());
		} nextInt {
			return Integer.parseInt(next());
		} return Integer.parseInt(next()); Integer.parseInt(next()) Integer.parseInt Integer next() next long nextLong() {
			return Long.parseLong(next());
		} nextLong {
			return Long.parseLong(next());
		} return Long.parseLong(next()); Long.parseLong(next()) Long.parseLong Long next() next double nextDouble() {
			return Double.parseDouble(next());
		} nextDouble {
			return Double.parseDouble(next());
		} return Double.parseDouble(next()); Double.parseDouble(next()) Double.parseDouble Double next() next String nextLine() {
			String str = "";
			try {
				str = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return str;
		} nextLine {
			String str = "";
			try {
				str = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return str;
		} String str = ""; str "" try {
				str = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			} catch (IOException e) {
				e.printStackTrace();
			} IOException e {
				e.printStackTrace();
			} e.printStackTrace() e.printStackTrace e {
				str = br.readLine();
			} str = br.readLine() str br.readLine() br.readLine br return str; str public class Main {

	static long expo(long base, long exp) {
		long t = 1L;
		while (exp > 0) {
			if (exp % 2 != 0)
				t = (t * base);

			base = (base * base);
			exp /= 2;
		}
		return t;
	}

	public static void main(String args[]) throws Exception {
		MyScanner sc = new MyScanner();
		PrintWriter pr = new PrintWriter(System.out);
		String a = sc.nextLine() , b = sc.nextLine();
		
		if(a.equals(b.substring(0, b.length() - 1)))
			System.out.println("Yes");
		else
			System.out.println("No");
		pr.close();
	}

	public static class MyScanner {
		BufferedReader br;
		StringTokenizer st;

		public MyScanner() {
			br = new BufferedReader(new InputStreamReader(System.in));
		}

		String next() {
			while (st == null || !st.hasMoreElements()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}

		int nextInt() {
			return Integer.parseInt(next());
		}

		long nextLong() {
			return Long.parseLong(next());
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}

		String nextLine() {
			String str = "";
			try {
				str = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return str;
		}
	}
} public class Main {

	static long expo(long base, long exp) {
		long t = 1L;
		while (exp > 0) {
			if (exp % 2 != 0)
				t = (t * base);

			base = (base * base);
			exp /= 2;
		}
		return t;
	}

	public static void main(String args[]) throws Exception {
		MyScanner sc = new MyScanner();
		PrintWriter pr = new PrintWriter(System.out);
		String a = sc.nextLine() , b = sc.nextLine();
		
		if(a.equals(b.substring(0, b.length() - 1)))
			System.out.println("Yes");
		else
			System.out.println("No");
		pr.close();
	}

	public static class MyScanner {
		BufferedReader br;
		StringTokenizer st;

		public MyScanner() {
			br = new BufferedReader(new InputStreamReader(System.in));
		}

		String next() {
			while (st == null || !st.hasMoreElements()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}

		int nextInt() {
			return Integer.parseInt(next());
		}

		long nextLong() {
			return Long.parseLong(next());
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}

		String nextLine() {
			String str = "";
			try {
				str = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return str;
		}
	}
} Main


import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.StringTokenizer;

public class Main {

	static long expo(long base, long exp) {
		long t = 1L;
		while (exp > 0) {
			if (exp % 2 != 0)
				t = (t * base);

			base = (base * base);
			exp /= 2;
		}
		return t;
	}

	public static void main(String args[]) throws Exception {
		MyScanner sc = new MyScanner();
		PrintWriter pr = new PrintWriter(System.out);
		String a = sc.nextLine() , b = sc.nextLine();
		
		if(a.equals(b.substring(0, b.length() - 1)))
			System.out.println("Yes");
		else
			System.out.println("No");
		pr.close();
	}

	public static class MyScanner {
		BufferedReader br;
		StringTokenizer st;

		public MyScanner() {
			br = new BufferedReader(new InputStreamReader(System.in));
		}

		String next() {
			while (st == null || !st.hasMoreElements()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}

		int nextInt() {
			return Integer.parseInt(next());
		}

		long nextLong() {
			return Long.parseLong(next());
		}

		double nextDouble() {
			return Double.parseDouble(next());
		}

		String nextLine() {
			String str = "";
			try {
				str = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return str;
		}
	}
}