/in/foo.cc: In function 'int main()':
/in/foo.cc:8:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i=0;i<strlen(s);i++)
              ~^~~~~~~~~~
/in/foo.cc:9:9: warning: array subscript has type 'char' [-Wchar-subscripts]
   a[s[i]]++;
         ^
/in/foo.cc:11:9: warning: array subscript has type 'char' [-Wchar-subscripts]
   if(a[i]!=0)
         ^
/in/foo.cc:14:9: warning: array subscript has type 'char' [-Wchar-subscripts]
   if(a[i]!=0)
         ^
/in/foo.cc:15:13: warning: array subscript has type 'char' [-Wchar-subscripts]
    cout<<a[i];
             ^