Legacy Code

Your software consists of packages and executables. Each method is Package::Method. Executables are packages whose method named PROGRAM starts running.

For every method you know which methods call it directly. A method is unused if no execution starting from any PROGRAM method can ever call it. Count unused methods.

Line 1: integer $N$ ($1 \leq N \leq 400$), the number of methods. Each method occupies two lines: identifier and caller count $k_i$, then optionally $k_i$ caller identifiers.

Print the number of unused methods.