There are n people in a party. Each person can either join dance as a single individual or as a pair with any other. Find the number of different ways in which all n people can join the dance.
One integer n (1≤n≤105).
Print the number of different ways in which all n people can join the dance. Print the answer modulo 109+7.
Let we have n=3 people. They can dance in 4 ways: {1,2,3},{{1,2},3},{1,{2,3}},{{1,3},2}.