text: If difference is negative , add N to it
code: if ( i - Aindex [ B [ i ] ] < 0 ) { if ( ! diff . ContainsKey ( A . Length + i - Aindex [ B [ i ] ] ) ) { diff [ A . Length + i - Aindex [ B [ i ] ] ] = 1 ; } else { diff [ A . Length + i - Aindex [ B [ i ] ] ] += 1 ; } }