/in/foo.cc: In function 'int main()':
/in/foo.cc:31:8: warning: iteration 24 invokes undefined behavior [-Waggressive-loop-optimizations]
   k[i] = i;
   ~~~~~^~~
/in/foo.cc:30:20: note: within this loop
  for (int i = 1; i <= 25; i++) 
                  ~~^~~~~