Option Explicit On

Module Module1

    Sub Main()

        Dim S As String = Console.ReadLine()
        Dim T As String = Console.ReadLine()

        If Len(S) + 1 = Len(T) Then
            If S = Left(T, Len(T) - 1) Then
                Console.WriteLine("Yes")
                End
            End If
        End If
        Console.WriteLine("No")

    End Sub
End Module
