foo.cc: In function 'int main()':
foo.cc:9:10: warning: unused variable 'num' [-Wunused-variable]
    9 |  int i,j,num;
      |          ^~~
foo.cc:17:8: warning: 'cnt' may be used uninitialized in this function [-Wmaybe-uninitialized]
   17 |  cout<<cnt;
      |        ^~~

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