In function 'void QuickSort(int*, int, int)',
    inlined from 'void MergeSubs(int*, int)' at foo.cc:57:18:
foo.cc:27:19: warning: 'k' may be used uninitialized [-Wmaybe-uninitialized]
   27 |         int p=Area(a,low,high);
      |               ~~~~^~~~~~~~~~~~
foo.cc: In function 'void MergeSubs(int*, int)':
foo.cc:36:17: note: 'k' was declared here
   36 |     int cnt=1,o,k;
      |                 ^
foo.cc:52:9: warning: 'o' may be used uninitialized [-Wmaybe-uninitialized]
   52 |         if(a[i]==o)
      |         ^~
foo.cc:36:15: note: 'o' was declared here
   36 |     int cnt=1,o,k;
      |               ^

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