class Solution {
    
    
public:
    const int mod = 1e9 + 7;
    int numWays(int n) {
    
    
        if(n == 0 || n == 1) return 1;
        int a = 1, b = 1;
        for(int ii = 2; ii <= n; ii++) {
    
    
            int temp = b;
            b = (int)(a + b) % mod;
            a = temp;
        }
        return b;
    }
};