foo.cc: In function 'int main()':
foo.cc:43:17: warning: unused variable 'k' [-Wunused-variable]
   43 |         long n, k=0, x=0;
      |                 ^
foo.cc:43:22: warning: unused variable 'x' [-Wunused-variable]
   43 |         long n, k=0, x=0;
      |                      ^
foo.cc: In function 'int ci(int, int)':
foo.cc:39:1: warning: control reaches end of non-void function [-Wreturn-type]
   39 | }
      | ^

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