/in/foo.cc: In function 'int main()':
/in/foo.cc:37:35: warning: iteration 233332 invokes undefined behavior [-Waggressive-loop-optimizations]
     for(int i=1;i<=MAXN;i++) fa[i]=i;
                              ~~~~~^~
/in/foo.cc:37:18: note: within this loop
     for(int i=1;i<=MAXN;i++) fa[i]=i;
                  ^