foo.cc: In function 'int main()':
foo.cc:5:13: warning: unused variable 'a' [-Wunused-variable]
    5 |         int a,b,k,i,n;
      |             ^
foo.cc:5:17: warning: unused variable 'k' [-Wunused-variable]
    5 |         int a,b,k,i,n;
      |                 ^

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