# include<iostream> # include<cstdio> using namespace std; int main() { int k,n=1,n1,n2,i; cin>>k; if(k==1||k==2){ cout<<1; } else{ n1=1; n2=1; for(i=3;i<=k;i++){ n=n1+n2; n1=n2; n2=n; } cout<<n; } return 0; }