foo.cc: In function 'int main()':
foo.cc:6:14: warning: unused variable 'f' [-Wunused-variable]
    6 |  int n,ans=0,f=0,it;
      |              ^
foo.cc:6:18: warning: unused variable 'it' [-Wunused-variable]
    6 |  int n,ans=0,f=0,it;
      |                  ^~

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