Using the cpp.sh compiler with all 3 warning levels on:
In function 'int main()':
39:38: warning: suggest braces around empty body in an 'if' statement [-Wempty-body]
49:22: warning: suggest braces around empty body in an 'if' statement [-Wempty-body]
52:22: warning: suggest braces around empty body in an 'if' statement [-Wempty-body]
55:21: warning: suggest braces around empty body in an 'if' statement [-Wempty-body]
11:12: warning: unused variable 'cottage_rent' [-Wunused-variable]
So you need to get rid of the semicolons at the ends of those lines, and use elseif, and use else to catch bad input. Always use braces, even if there is only 1 statement attached to a conditional.
Avoid using hard coded magic numbers like 60 and 400 in your code, make them const variables instead.