Operation Files 2.1. Your program should open and read the file specified by the first command line argument of the program.
2.2. The first line of the file contains an integer that indicates the size with which to construct the SVector. Your program should catch the STL exception thrown by the STL vector class in main(), and report it before terminating.
2.3. Each line of the file starts with a char. 2.3.1.If the char is a 'U', then there is an integer followed by a string on the line with which to call push_back.
2.3.2.If the char is an 'A', then it is followed by a string with which to access the SVector using []. Your program should print out the corresponding integer, or throw an exception if the string is an invalid index.
2.3.3.If the char is an 'O', then it is followed by nothing. Normally, your main() should print nothing, but it should catch the exception if the vector is empty. Your SVector::pop_back() should update the map so the string to int mapping is removed. This is a little tricky, since you have only the int from the vector size() with which to work.