content: when he woke the girl had disappeared , and he got up , and returned to the byre . as he drew near , he rubbed his eyes hard , thinking he was dreaming , for there it was , beautifully thatched , just as the giant had wished . at the door of the house he met the giant . ' hast thou thatched the byre , king 's son ? ' ' i have thatched it . ' ' well , since thou hast been so active to - day , i have something else for thee ! beside the loch thou seest over yonder there grows a fir tree . on the top of the fir tree is a magpie 's nest , and in the nest are five eggs . thou wilt bring me those eggs for breakfast , and if one is cracked or broken , thy blood shall pay for it . ' before it was light next day , the king 's son jumped out of bed and ran down to the loch . the tree was not hard to find , for the rising sun shone red on the trunk , which was five hundred feet from the ground to its first branch . time after time he walked round it , trying to find some knots , however small , where he could put his feet , but the bark was quite smooth , and he soon saw that if he was to reach the top at all , it must be by climbing up with his knees like a sailor . but then he was a king 's son and not a sailor , which made all the difference .
answer: the bark was quite smooth .
question: why was it difficult to climb the tree ?
target: why was it difficult to climb the tree ?
references: why was it difficult to climb the tree ?