https://www.acmicpc.net/problem/2747
import java.util.*;
public class Main {
public static void main(String args[]) {
Scanner s=new Scanner(System.in);
int n=s.nextInt();
int f[]=new int[n+1];
f[1]=1;
for(int i=2;i<=n;i++){
f[i]=f[i-1]+f[i-2];
}
System.out.print(f[n]);
}
}