Task: Program Execution
Input (English): u, 8091, 4309, 9883, 1261, 1731, f, 5201, 7581, 9443, r, u, B
Output (English): 21, 8091, 4309, 9883, 1261, 1731, 6, 5201, 7581, 9443, 18, 21, 2