#include <stdio.h>#define MAX 50+1int fib(int n){
int i,a[MAX]; a[1]=a[2]=1;
for (i=3; i<=n; i++) a[i]=a[i-1]+a[i-2]; return a[n];}void main( ){ int n; scanf("%d",&n); printf("%d " ,fib( n ) );}