#include <iostream> //designed by hu 2025-10 using namespace std; int main(){ int k,a,b,c; cin >> k; a = 1; b = 1; if (k==1 || k==2) { cout<< 1; return 0; //结束程序 } for(int i=1;i<= k-2 ;i++) { c = a + b; a = b; b = c; } cout << c; return 0; }