Divide 26, 33, 34, 35, 63, 85, 91, 143 into several groups, and require that the greatest common divisor of any two numbers in each group is 1, then at least how many groups should be divided into.
把26，33，34，35，63，85，91，143分成若干组，要求每一组中任意两个数的最大公约数是1，那么至少要分成多少组．
<result>3</result>