AMO · 2027 · Grades 6-7 · Self-study SET 25 Question 12

Nicholas writes the positive integers from 1 to 50 in an ordered list. On Monday he crosses out every multiple of 2; on Tuesday every multiple of 3; on Wednesday every multiple of 5; on Thursday every multiple of 7; on Friday every multiple of 11; and on Saturday every multiple of 13. How many of the original 50 integers are not crossed out?

**Input:** Choose one option.