Task: Program Execution
Input (English): x, t, R, 6487, o, 2771, M, 9551, 4519, Y, 7633, l, a, 5371, 3681, i, 7917, 2619, 2427, 8143, 9491, N, L, N
Output (English): 4, 6, 8, 9, 11, 14, 15, 17, 18, 19, 20, 21