package leetcode;

public class demo_70 {
    public int climbStairs(int n) {
        int[] f= new int[n+1];
        f[1]=1;
        try {
            f[2]=2;
        } catch (Exception e) {
            // TODO: handle exception
        }
        for(int i=3;i<=n;i++) {
            f[i]=f[i-1]+f[i-2];
        }
        return f[n];
    }
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        demo_70 d70=new demo_70();
        System.out.println(d70.climbStairs(4));
    }

}