/in/foo.cc: In function 'int main()':
/in/foo.cc:11:20: error: 'isdigt' was not declared in this scope; did you mean 'isdigit'?
   11 |                 if(isdigt(a[i])){
      |                    ^~~~~~
      |                    isdigit
/in/foo.cc:12:30: warning: array subscript has type 'char' [-Wchar-subscripts]
   12 |                         b[a[i]]++;
      |                           ~~~^