/in/foo.cc: In function 'int main()':
/in/foo.cc:25:10: warning: iteration 29 invokes undefined behavior [-Waggressive-loop-optimizations]
   a[1][i]=1;
   ~~~~~~~^~
/in/foo.cc:24:15: note: within this loop
  for(int i=1;i<=N;i++)
              ~^~~
/in/foo.cc:17:10: warning: iteration 29 invokes undefined behavior [-Waggressive-loop-optimizations]
   C[i][0]=1;
   ~~~~~~~^~
/in/foo.cc:15:15: note: within this loop
  for(int i=1;i<=N;i++)
              ~^~~