foo.cc: In function 'int cmp(std::string, std::string)':
foo.cc:17:13: warning: array subscript has type 'char' [-Wchar-subscripts]
   17 |  if (a[a1[i]]!=a[a2[i]]) return a[a1[i]]<a[a2[i]];
      |             ^
foo.cc:17:23: warning: array subscript has type 'char' [-Wchar-subscripts]
   17 |  if (a[a1[i]]!=a[a2[i]]) return a[a1[i]]<a[a2[i]];
      |                       ^
foo.cc:17:40: warning: array subscript has type 'char' [-Wchar-subscripts]
   17 |  if (a[a1[i]]!=a[a2[i]]) return a[a1[i]]<a[a2[i]];
      |                                        ^
foo.cc:17:49: warning: array subscript has type 'char' [-Wchar-subscripts]
   17 |  if (a[a1[i]]!=a[a2[i]]) return a[a1[i]]<a[a2[i]];
      |                                                 ^
foo.cc: In function 'int main()':
foo.cc:23:32: warning: array subscript has type 'char' [-Wchar-subscripts]
   23 |   for (int i=0;i<26;i++) a[b[i]]=i;
      |                                ^

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