#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
// Yukicoder №44 DPなすごろく ★★
// https://yukicoder.me/problems/no/44
// ***********************
// for debug
#define DEBUG
// -----------

#define NOP do{}while(0)
#ifdef DEBUG
#define TRACE(...) do{printf(__VA_ARGS__);fflush(stdout);}while(0)
#define TRACECR do{putchar_unlocked('\n');fflush(stdout);}while(0)
#else
#define TRACE(...) NOP
#define TRACECR NOP
#endif

#define	mypc(d)	putchar_unlocked((int)(d))
#define PRINCR mypc('\n')
#define NOCR(strig) do{char *p;p=strchr(strig,'\n');if(p)*p='\0';}while(0)
// The out-of-date function
#define	asctime(...)	asctime_s(...)
#define	ctime(...)		ctime_s(...)
#define	strlen(a)	mystr_len(a)

// for stdio
#define GETLINE(str) do{char *p;fgets(str,sizeof(str),stdin);p=strchr(str,'\n');if(p)*p='\0';}while(0)
#define mygc(c) (c)=getchar_unlocked()
static char *GETWORD(char* str) {char c;char *cp;cp=&str[0];mygc(c);while(c!=EOF){if((c==' ')||(c=='\n'))break;*cp++=c;mygc(c);}*cp='\0';return &str[0];}
#define	GETINTS(a,b) {char s[34];int *ap=a;REP(i,b){GETWORD(s);*ap++=atoi(s);}}
static int GETLINEINT(void) {char s[34];GETLINE(s);return atoi(s);}
static int GETWORDINT(void) {char s[34];GETWORD(s);return atoi(s);}
static long GETWORDLONG(void) {char s[34];GETWORD(s);return atol(s);}
static int maxi(int a,int b){if((a)>(b)){return a;}return b;}
static long maxl(long a,long b){if(a>b){return a;}return b;}
#define SWAP(type,a,b) do{type _c;_c=a;a=b;b=_c;}while(0)
#define REP(a,b) for(int a=0;a<(int)(b);++a)
#define REP1(a,b) for(int a=1;a<=(int)(b);++a)
#define Possible(a) 	   printf("%s",((a)?"Possible":"Impossible"))
#define possible(a) 	   printf("%s",((a)?"possible":"impossible"))

// *********************
// *********************
#define	fibo(c)	(FibonacciNumber[(c)])
// フィボナッチ数列（0～92） 93以降は64bitで表せない
const long long FibonacciNumber[] = {
1,1,2,3,5,8,13,21,34,55,89,144,233,377,610,987,1597,2584,4181,6765,10946,17711,
28657,46368,75025,121393,196418,317811,514229,832040,1346269,2178309,3524578,
5702887,9227465,14930352,24157817,39088169,63245986,102334155,165580141,
267914296,433494437,701408733,1134903170,1836311903,2971215073,4807526976,
7778742049,12586269025,20365011074,32951280099,53316291173,86267571272,
139583862445,225851433717,365435296162,591286729879,956722026041,1548008755920,
2504730781961,4052739537881,6557470319842,10610209857723,17167680177565,
27777890035288,44945570212853,72723460248141,117669030460994,190392490709135,
308061521170129,498454011879264,806515533049393,1304969544928657,
2111485077978050,3416454622906707,5527939700884757,8944394323791464,
14472334024676221,23416728348467685,37889062373143906,61305790721611591,
99194853094755497,160500643816367088,259695496911122585,420196140727489673,
679891637638612258,1100087778366101931,1779979416004714189,2880067194370816120,
4660046610375530309,7540113804746346429 };
// *********************
int main( void ) {
	int	N = GETLINEINT();
    printf("%lld\n", fibo( N ) );
}