foo.cc: In function 'int main()':
foo.cc:7:10: warning: unused variable 'i' [-Wunused-variable]
  for(int i=1;;)
          ^
foo.cc:5:16: warning: unused variable 'b' [-Wunused-variable]
  int n,cnt=0,a,b;
                ^
foo.cc:11:4: warning: 'a' may be used uninitialized in this function [-Wmaybe-uninitialized]
   a+=(n%10)*(n%10);
   ~^~~~~~~~~~~~~~~

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