21) а) 567,576,657,675,765,756
б) 012,021,102,120,201,210
22) а) 567,576,566,577,557,556,555,777,666,657,675,655,677,665,667,765,756,776,775,766,755,767,757,656,676,575,565
б) 012,011,022,002,001,021,000,111,222,102,120,122,100,110,112,200,201,210,221,220,202,101,010,020,