Definition: Given a math word problem, answer the following question. You might need to apply addition or subtraction mathematical operators on the numbers embedded in the text to answer the question and then only report the final numerical answer.
Input: maura collects seashells every summer . her family stays at the beach house for 21 days . this summer maura found 75 seashells . she gave some to her little sister . maura then had 57 seashells . how many seashells did maura give to her sister ?
Output:
18