One Decremented

Have the function OneDecremented(str) count how many times a digit appears that is exactly one less than the previous digit. For example: if str is "5655984" then your program should return 2 because 5 appears directly after 6 and 8 appears directly after 9. The input will always contain at least 1 digit.

Examples

Input: "56"
Output: 0

Input: "9876541110"
Output: 6