/in/foo.cc: In function 'int main()':
/in/foo.cc:8:6: warning: unused variable 'len1' [-Wunused-variable]
  int len1 = 0, len2 = 0;
      ^
/in/foo.cc:8:16: warning: unused variable 'len2' [-Wunused-variable]
  int len1 = 0, len2 = 0;
                ^