#include <cstdio>
char F[2][201];
int main(){
    FILE*fi;
    fi=fopen("nunta.in","r");
    short n;
    fscanf(fi,"%hd", &n);
    fclose(fi);
    fi=fopen("nunta.out","w");
    if(n == 1){
        fprintf(fi,"1");
        return 0;
    }
    F[0][1] = 1;
    F[1][1] = 2;
    unsigned char i, t;
    short j;
    for(j = 3; j <= n; j++){
        t = 0;
        for(i = 1; i <= 199 || t; i++, t/=10)
            F[1 - j % 2][i] = (t += F[0][i] + F[1][i]) % 10;
    }
    i = 199;
    while(F[1 - n % 2][i] == 0) i--;
    while(i > 0)
        fputc(F[1 - n % 2][i--] + '0', fi);
    return 0;
}