foo.cc: In function 'int main()':
foo.cc:31:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<s1.length();i++)
              ~^~~~~~~~~~~~
foo.cc:33:16: warning: array subscript has type 'char' [-Wchar-subscripts]
   if(flag[s1[i]]&&s2[i]^table[s1[i]])
                ^
foo.cc:40:13: warning: array subscript has type 'char' [-Wchar-subscripts]
   flag[s1[i]]=true;
             ^
foo.cc:45:19: warning: array subscript has type 'char' [-Wchar-subscripts]
   if(flag[table[i]])
                   ^
foo.cc:50:16: warning: array subscript has type 'char' [-Wchar-subscripts]
   flag[table[i]]=true;
                ^

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