#include <stdio.h>

#define MAXSIZE 1000

char n1[MAXSIZE], n2[MAXSIZE], n3[MAXSIZE];

char *f1 = n1, *f2 = n2, *f3 = n3, *t;

void set1(char *n1){
   int i;
   n1[0]=1;
   for (i=1;i<MAXSIZE;i++){
      n1[i]  = 0;
   }
}

void add( char *n1, char *n2, char *n3){
   int i;
   for (i=0;i<MAXSIZE;i++){
      n3[i] = 0;
   }
   for (i=0;i<MAXSIZE;i++){
      n3[i] = n1[i] + n2[i] + n3[i];
      if (n3[i] >= 10) {
         n3[i] -= 10;
         n3[i+1] = 1;
      }
   }
}

void prn(char *n1){
   int i;
   for (i=MAXSIZE-1;i>=0 && !n1[i];i--){}
   if (i<0) i = 0;
   for (;i>=0;i--) {
      printf("%d",n1[i]);
   }
   printf("\n");
}

main(){
   int i,j,k;
   
   while (1 == scanf("%d\n",&k)){
      set1(f1);
      set1(f2);
      for (i=0;i<k;i++){
         add(f1,f2,f3);
         t = f1;
         f1 = f2;
         f2 = f3;
         f3 = t;
      }
      prn(f3);
   }
}