C++ :: Using Cin That Accept Multiple Inputs

For a program I am required to use a cin that accepts 4 variables. The first describes a function such as add(), remove(), print(), or quit(). The problem is that to use add() I need to input all 4 variables but for remove(), only 2 variable input is needed.

I want the input to be "add 9 James Bond"
or be "remove 341"

Here is my current code.

int command(string command, int Id, string first, string last){
while (command != "quit"){
cout << "customers> ";
cin >> command >> Id >> first >> last;
if (command == "add")

[Code] .....