View Compilation Error

0_0_37210492_3009.cpp: In member function 'int mine::SA::query(int, int)':
0_0_37210492_3009.cpp:128:35: error: 'retun' was not declared in this scope
   int query(int l,int r){ if(l>r) retun 0; return sum[r]-sum[l-1]; }
                                   ^