/in/foo.cc: In function 'void init()':
/in/foo.cc:31:53: warning: iteration 50009 invokes undefined behavior [-Waggressive-loop-optimizations]
  for(int i = 1; i <= N; i ++) s[i] = s[i - 1] + mu[i];
                                                 ~~~~^
/in/foo.cc:31:19: note: within this loop
  for(int i = 1; i <= N; i ++) s[i] = s[i - 1] + mu[i];
                 ~~^~~~
/in/foo.cc:16:12: warning: iteration 50008 invokes undefined behavior [-Waggressive-loop-optimizations]
   if (!st[i]) {
        ~~~~^
/in/foo.cc:15:20: note: within this loop
  for (int i = 2; i <= N; i ++) {
                  ~~^~~~