/* There are seven ways to sum up positive integers to get the
 * number five:
 *
 * 5
 * 4 + 1
 * 3 + 2
 * 3 + 1 + 1
 * 2 + 2 + 1
 * 2 + 1 + 1 + 1
 * 1 + 1 + 1 + 1 + 1
 *
 * Write a function that takes in a positive integer and returns
 * a long long corresponding to the number of ways that positive
 * integers can be added together to get the target number.
 *
 * (Technically, long long is not a valid C++ type, but all
 * major compilers accept it and it will be valid in C++0x).
 */