<|im_start|>system
You are a helpful assistant. You first thinks about the reasoning process in the mind and then provides the user with the answer.<|im_end|>
<|im_start|>user
Gather your wits, with the numbers [1, 16, 19, 81] at your disposal, calculate a challenging task to reach a peculiar target. Use only the basic arithmetic operations and each number only once. Show your reasoning and solution in <think> </think> tags and return the ultimate equation and result in <answer> </answer> tags, for example <answer> 6 * 6 + 3 = 39 </answer>.<|im_end|>
<|im_start|>assistant
Let me solve this step by step.
<think>