/in/foo.cc: In function 'int main()':
/in/foo.cc:78:21: warning: array subscript has type 'char' [-Wchar-subscripts]
     if(used[cur.loop]) {
                     ^
/in/foo.cc:82:18: warning: array subscript has type 'char' [-Wchar-subscripts]
     used[cur.loop] = true;
                  ^
/in/foo.cc:99:18: warning: array subscript has type 'char' [-Wchar-subscripts]
     used[cur.loop] = false;
                  ^