VÒNG 4 - L P 1 (10-10-2014)Ớ
1 < 1+1 < 2+1 < 2+2 < 2+3 < 6 < 7 < 8 < 9 < 10
2+1 = 1+2 ; 2+3 = 4+1 ;
1
2