```
class Solution {
public:
static double sqrt5;
static double a;
static double b;
static double c;
int climbStairs(int n) {
return (int)(a* (pow(b, n+1) - pow(c, n+1)) + 1e-6);
}
};
double Solution::sqrt5 = 2.2360679774997896964091736687313;
double Solution::a = 1/Solution::sqrt5;
double Solution::b = (1+Solution::sqrt5)/2;
double Solution::c = (1-Solution::sqrt5)/2;
```