Task: Program Execution
Input (English): 1523, i, r, 6423, z, m, j, 2573, 8491, 8367, X, 2251, P, X, w, 7367, 2507, S, 597, 1745, 2917, 2921, 6771
Output (English): 2, 3, 5, 6, 7, 11, 13, 14, 15, 18