#include<cstdio>
unsigned char a[210],b[210];
int main() {
    unsigned char n,t,i;
    freopen("nunta.in","r",stdin),freopen("nunta.out","w",stdout),scanf("%hd",&n);
    for(a[0]=b[0]=a[1]=b[1]=1;n>1;n--) {
        for(t=0,i=1;i<=a[0]||i<=b[0]||t;i++,t/=10)
            b[i]=(t+=a[i]+b[i])%10;
        for(b[0]=i-1,t=0,i=1;i<=b[0];i++)
            a[i]=b[i]-((i<=a[0])?a[i]:0)-t,a[i]+=(t=a[i]<0)*10;
        for(a[0]=i-1;a[0]>1&&!a[a[0]];a[0]--);
    }
    for(i=b[0];i;i--)
        printf("%hd",b[i]);
}