INPUT	OUTPUT
John Doe 333224444 DoeJ 123Password	John Doe xxxxxxxxx DoeJ xxxxxxxxxxx
Jane Smith 296487534 SmithJ 123456789Hey	Jane Smith xxxxxxxxx SmithJ xxxxxxxxxxxx

Write a program that reads in a line consisting of a student's name, Social Security number, user ID, and password. The program outputs the string in which all the digits of the Social Security number and all the characters in the password are replaced by x. (The Social Security number is in the form 000-00-0000, and the user ID and the password do not contain any spaces.) Your program should not use the operator [] to access a string element. Use the appropriate functions below.

Expression	Effect
strVar.at(index)	Returns the element at the position specified by index
strVar[index]	Returns the element at the position specified by index
strVar.append(n, ch)	Appends n copies of ch to strVar, where ch is a char variable or a char constant
strVar.append(str)	Appends str to strVar
strVar.clear()	Deletes all the characters in strVar
strVar.compare(str)	Returns 1 if strVar > str returns 0 if strVar == str; returns 1 if strVar < str
strVar.empty()	Returns true if strVar is empty; otherwise it returns false
strVar.erase()	Deletes all the characters in strVar
strVar.erase(pos, n)	Deletes n characters from strVar starting at position pos
strVar.find(str)	Returns the index of the first occurrence of str in strVar. If str is not found, the special value string::npos is returned
strVar.find(str, pos)	Returns the index of the first occurrence at or after pos where str is found in strVar
strVar.find_first_not_of(str, pos)	Returns the index of the first occurrence of any character of strVar in str. The search starts at pos
strVar.insert(pos, n, ch)	Inserts n occurrences of the character ch at index pos into strVar; pos and n are of type string::size_type; and ch is a character
strVar.insert(pos, str)	Inserts all the characters of str at index pos into strVar
strVar.length()	Returns a value of type string::size_type giving the number of characters in strVar
strVar.replace(pos, n, str)	Starting at index pos, replaces the next n characters of strVar with all the characters of str. If n > length of strVar, then all the characters until the end of strVar are replaced
strVar.substr(pos, len)	Returns a string which is a substring of strVar starting at pos. The length of the substring is at most len characters. If len is too large, it means "to the end" of the string in *strVar
strVar.size()	Returns a value of type string::size_type giving the number of characters in strVar
strVar.swap(str1)	Swaps the contents of strVar and str1. str1 is a string variable