#include<stdio.h>
char a[81],b[81],c[81];
int i,n,t;
int main() {
    freopen("nunta.in","r",stdin),freopen("nunta.out","w",stdout),scanf("%d",&n),n++,b[0]=b[1]=1;
    while(n--) {
        for(t=0,i=1;i<=a[0]||i<=b[0]||t;i++,t/=10)
            c[i]=(t+=a[i]+b[i])%10;
        c[0]=i-1;
        for(i=0;i<=b[0];i++)
            a[i]=b[i];
        for(i=0;i<=c[0];i++)
            b[i]=c[i];
    }
    for(i=a[0];i;i--)
        printf("%d",a[i]);
}