foo.cc: In function 'int main()':
foo.cc:9:10: warning: 'i' is used uninitialized in this function [-Wuninitialized]
  a[i]=a[i-1]+a[i-2];
         ~^~
foo.cc:9:12: warning: 'a[<unknown>]' is used uninitialized in this function [-Wuninitialized]
  a[i]=a[i-1]+a[i-2];
       ~~~~~^
foo.cc:9:19: warning: 'a[<unknown>]' is used uninitialized in this function [-Wuninitialized]
  a[i]=a[i-1]+a[i-2];
              ~~~~~^

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