/in/foo.cc: In function 'int main()':
/in/foo.cc:8:14: warning: iteration 10 invokes undefined behavior [-Waggressive-loop-optimizations]
   if(n+30>a[i]) res++;
           ~~~^
/in/foo.cc:7:18: note: within this loop
     for(int i=0;i<=10;i++)
                 ~^~~~
/in/foo.cc:8:22: warning: 'res' may be used uninitialized in this function [-Wmaybe-uninitialized]
   if(n+30>a[i]) res++;
                      ^