#include<iostream> #include<cstdio> //scanf()\printf() #include<cstring> #include<cmath> //sqrt()\pow()\abs()\ceil()\floor()\max()\min() using namespace std; int main(){ int a=1,b=1,sum=1,k; cin>>k; for(int i=3;i<=k;i++){ sum=a+b; a=b; b=sum; } cout<<sum; return 0; }