foo.cc: In function 'void Count(char*, int*)':
foo.cc:6:22: warning: comparison of integer expressions of different signedness: 'int' and 'size_t' {aka 'long unsigned int'} [-Wsign-compare]
    6 |         for(int i=0;i<strlen(s);i++)
      |                     ~^~~~~~~~~~
foo.cc:11:30: warning: array subscript has type 'char' [-Wchar-subscripts]
   11 |                         a[s[i]]++;
      |                           ~~~^

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