Task: Program Execution
Input (English): 6147 6673 b 5129 6299 4143 8443 765 B e 6511 X z 3427 8285 1177 2159 8637 8839 Z 2255 d x k n 1707 6777 9987 u y
Output (English): 1, 2, 4, 5, 6, 7, 8, 11, 14, 15, 16, 17, 18, 19, 21, 26, 27, 28