Task: Program Execution
Input (English): 6121, 6801, b, 1905, d, 4021, 1279, x, 6775, 2877, 6723, 7845, m, 6981, 5397, 59, l, 4267, k, B, 3867, o, u, b
Output (English): 6121, 6801, 1905, 4021, 1279, 6775, 2877, 6723, 7845, 6981, 5397, 59, 4267, 3867