Number of Triples

Write a program that reads an array of ints and outputs the number of "triples" in the array.

A "triple" is three consecutive ints in increasing order differing by 1 (i.e. ```3,4,5``` is a triple, but ```5,4,3``` and ```2,4,6``` are not).
```
Sample Input:
6
1 2 4 5 6 7

Sample Output:
2

Sample Input:
6
1 4 7 5 4 3

Sample Output:
0
```