a b b c a c a b c a x1 a b c a c a b b c a c a b x1 2.2 a b b c a c a b c a x1 a c a b b c a c a b x1 a b b c a c a b c a x1 a b x1 a b b c a c a b c a x1 a b b c a c a b x1 a b b c a c a b c a x1 a b c a c a b b c a c a b x1 a b b c a c a b c a x1 a c a b x1 true a b b c a c a b c a x1 a b b c a c a b x1 a b b c a c a b c a x1 a b x1 true Failed! NaTT certifiable-1.6