300
To correct this improperly punctuated sentence, we just need to separate the locations with commas and place a period at the end.
"Last October we traveled overseas and visited Barcelona Spain Paris France and Rome Italy"
What is "false"?
This is a complicated list. We want the reader to understand that the city and the country are grouped as a pair. If we place a comma after each location, it will not be clear that the city and the country are a grouped entity in this list. Therefore, we need to separate the city and the country with a comma and separate each grouping with a semicolon.
"Last October we traveled overseas and visited Barcelona, Spain; Paris, France; and Rome, Italy"