/in/foo.cc: In function 'int main()':
/in/foo.cc:12:22: error: 'ans' was not declared in this scope
   if(b[j]>=a[i]) j--,ans++;
                      ^~~
/in/foo.cc:15:19: error: 'ans' was not declared in this scope
     printf("%d\n",ans);
                   ^~~