/in/foo.cc: In function 'int find(int, int, int)':
/in/foo.cc:20:10: warning: variable 'ans' set but not used [-Wunused-but-set-variable]
  int mid,ans;
          ^~~
/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]);
          ~^~~~~~~~~~~~~~~~~