Mr Y and his Transport Problem

Mr X has a huge transport business, where his company provides trucks to transfer goods. Mr Y has a manufacturing facility where it has N number of loading areas. Mr Y orders N trucks from Mr X for transportation of each of its manufactured products. One day the trucks were misaligned corresponding to their loading areas. Mr Y wants to swap trucks one by one to place them at their true positions in such a way that there is a minimum number of swaps between trucks. Note that all trucks are already at the misplaced loading area, swap occurs between two trucks at a time and truck is numbered based on its loading area number that is both loading area and truck have the same number and loading area are denoted by 1 to N.

Input:
1 <= N <= 50
1st Line: integer N which denotes the number of loading areas
2nd Line: N space-separated integers denoting truck numbers parked on 1 to N loading area.

Output:
Number denoting a _minimum number of swaps_.

**Sample input**
10
1 3 2 4 9 6 7 5 8 10

**Sample output**
3