/in/foo.cc: In function 'int calc(int, int*)':
/in/foo.cc:36:11: warning: operation on 'k' may be undefined [-Wsequence-point]
   else f[k=find(1,len,c[i])]=min(f[k],c[i]);
          ~^~~~~~~~~~~~~~~~~
/in/foo.cc: In function 'int find(int, int, int)':
/in/foo.cc:27:9: warning: 'ans' may be used uninitialized in this function [-Wmaybe-uninitialized]
  return ans;
         ^~~
/in/foo.cc: In function 'int calc(int, int*)':
/in/foo.cc:20:10: warning: 'ans' may be used uninitialized in this function [-Wmaybe-uninitialized]
  int mid,ans;
          ^~~