foo.cc: In function 'int main()':
foo.cc:6:19: warning: unused variable 'f' [-Wunused-variable]
    6 |     int a,b,c,d,e,f=0;cin>>a>>b;cout<<b-a<<endl;
      |                   ^
foo.cc:14:12: warning: 'e' may be used uninitialized in this function [-Wmaybe-uninitialized]
   14 |           e++;
      |           ~^~

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