int combination_lock ( int m, int n, int c[] );
void combination_next ( int m, int base, int a[], bool *more );
int i4_power ( int i, int j );
int i4_uniform_ab ( int a, int b, int *seed );
bool i4vec_eq ( int n, int a1[], int a2[] );
void i4vec_print ( int n, int a[], char *title );
void timestamp ( );