/in/foo.cc: In function 'int main()':
/in/foo.cc:92:6: warning: unused variable 'u' [-Wunused-variable]
  int u,v,len;
      ^
/in/foo.cc:92:8: warning: unused variable 'v' [-Wunused-variable]
  int u,v,len;
        ^
/in/foo.cc:92:10: warning: unused variable 'len' [-Wunused-variable]
  int u,v,len;
          ^~~