#include <stdio.h>
char F[2][200];
int main(){
    FILE*fi,*fo;
    fi=fopen("nunta.in","r");
    fo=fopen("nunta.out","w");
    short n;
    fscanf(fi,"%hd", &n);
    if(n == 1){
        fprintf(fo,"1");
        return 0;
    }
    F[0][1] = 1;
    F[1][1] = 2;
    bool ind = 1;
    for(short j = 3; j <= n; j++){
        unsigned char i, t = 0;
        for(i = 1; i <= 199 || t; i++, t/=10)
            F[1 - ind][i] = (t += F[0][i] + F[1][i]) % 10;
        ind = !ind;
    }
    unsigned char i = 199;
    while(F[ind][i] == 0) i--;
    while(i > 0)
        fprintf(fo,"%d", F[ind][i--]);
    return 0;
}