#include <iostream> using namespace std; int main() { int k; cin>>k; if(k == 0){ cout<< "0" <<endl; return 0; }else if(k == 1){ cout<<"1"<<endl; return 0; } int a=0,b=1,f=0; for (int i=2;i<=k;i++){ f=a+b; a=b; b=f; } cout<<f<<endl; return 0; }