/*
 *    Author:
 *        Indestinee
 *    Date:
 *        2016/05/14
 */
#include <map>
#include <set>
#include <cmath>
#include <cstdio>
#include <string>
#include <vector>
#include <cstring>
#include <iostream>
#include <algorithm>
using namespace std;
const int maxn = 1000, base = 10000;
#define len d[0]
class bignum{
private:
    int d[maxn];
    void clear(){
        memset( d , 0 , sizeof d );
    }
public:
    bignum(int x=0){
        clear();
        do{
            d[++len]=x % base;
            x /= base;
        }while( x );
    }
    void out(string s="",char a = '\n'){
        printf( "%d" , d[len] );
        for( int i = len - 1 ; i ; i -- )
            printf( "%04d" , d[i] );
        putchar( a );
    }
    friend bignum operator + ( const bignum &a , const bignum &b ){
        bignum ret;
        ret.len = max( a.len , b.len );
        int x = 0;
        for( int i = 1 ; i <= ret.len ; i ++ ){
            x = x + a.d[i] + b.d[i];
            ret.d[i] = x % base;
            x /= base;
        }
        while( x ){
            ret.d[++ret.len] = x % base;
            x /= base;
        }
        return ret;
    }
}f[6000];
int n;
int main(){
//    freopen( "B.in"  , "r" , stdin  );
//    freopen( "B.out" , "w" , stdout );
    f[0] = bignum(1);
    f[1] = bignum(1);
    f[2] = bignum(2);
    for( int i = 3 ; i < 6000 ; i ++ )
        f[i] = f[i-1] + f[i-2];
    while( scanf( "%d" , &n ) != EOF ){
        if( n == 0 ){
            puts( "" );
            continue;
        }
        f[n].out();
    }
    return 0;
}