#include<stdio.h>
char a[22],b[22],c[22];
short i,n,t;
int main() {
    freopen("nunta.in","r",stdin),freopen("nunta.out","w",stdout),scanf("%hd",&n),c[0]=c[1]=a[0]=b[0]=a[1]=b[1]=1;
    for(;n>1;n--) {
        memset(c,0,sizeof(c));
        for(t=0,i=1;i<=b[0]||i<=a[0]||t;i++,t/=10)
            c[i]=(t+=b[i]+a[i])%10;
        c[0]=i-1,memcpy(a,b,sizeof(b)),memcpy(b,c,sizeof(c));
    }
    for(i=c[0];i;i--)
        printf("%hd",c[i]);
}