#include<iostream> using namespace std; int main(){//相当于用递推法求斐波那契数列 int n; int counter[91]; counter[0] = 0; counter[1] = 1; counter[2] = 2; for(int i=3;i<=90;i++){ counter[i] = counter[i-1]+counter[i-2]; } while(cin>>n){ cout<<counter[n]<<endl; } return 0; }