foo.cc:2:2: error: invalid preprocessing directive #inde; did you mean #ifdef?
 #inde <cstdio>
  ^~~~
  ifdef
foo.cc: In function 'int main()':
foo.cc:7:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%f",&f);
  ~~~~~^~~~~~~~~

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