/in/foo.c: In function 'main':
/in/foo.c:17:2: error: unknown type name 'Section'; use 'struct' keyword to refer to the type
  Section section[100000];
  ^~~~~~~
  struct 
/in/foo.c:20:25: error: request for member 'u' in something not a structure or union
   scanf("%d",&section[i].u);
                         ^
/in/foo.c:21:25: error: request for member 'v' in something not a structure or union
   scanf("%d",&section[i].v);
                         ^
/in/foo.c:24:22: error: request for member 'u' in something not a structure or union
   answer(a,section[i].u,section[i].v);
                      ^
/in/foo.c:24:35: error: request for member 'v' in something not a structure or union
   answer(a,section[i].u,section[i].v);
                                   ^
/in/foo.c:17:10: warning: variable 'section' set but not used [-Wunused-but-set-variable]
  Section section[100000];
          ^~~~~~~