/in/foo.cc: In function 'int main()':
/in/foo.cc:7:29: error: 'n' was not declared in this scope
    7 |         int sum=(xmax+xmin)*n/2;
      |                             ^
/in/foo.cc:6:13: warning: unused variable 'i' [-Wunused-variable]
    6 |         int i=xmax-xmin+1;
      |             ^