/in/foo.cc: In function 'void init()':
/in/foo.cc:49:20: warning: iteration 1000008 invokes undefined behavior [-Waggressive-loop-optimizations]
             fib[i] = (fib[i-1] + fib[i-2]) % mod;
             ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/in/foo.cc:47:19: note: within this loop
     for (int i=2;i<=maxn;i++)
                  ~^~~~~~