foo.cc: In function 'int main()':
foo.cc:18:9: warning: unused variable 'len' [-Wunused-variable]
   18 |     int len=max(la,lb);
      |         ^~~
foo.cc:19:9: warning: unused variable 'jw' [-Wunused-variable]
   19 |     int jw=0;
      |         ^~

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