#include<cstdio>

int n,a[1001],b[1001];

void adun(){
    int i,aux,t=0;
    for(i=1; i<=b[0]; ++i){
        aux=b[i];
        b[i]=(a[i]+aux+t)%10;
        t=(a[i]+aux+t)/10;
        a[i]=aux;}
    if(t)
        b[++b[0]]=t;
}

void solve(){
    int i;
    scanf("%d",&n);
    b[0]=1;
    a[1]=1;
    b[1]=1;
    if(n==1)
        printf("1");
    else if(n==2)
        printf("1");
    else{
        for(i=3; i<=n+1; ++i)
            adun();
        i=b[0];
        while(b[i]==0)
            --i;
        for(i; i>0; --i)
            printf("%d",b[i]);
        }
}
int main(){
    freopen("nunta.in","r",stdin);
    freopen("nunta.out","w",stdout);
    solve();
    return 0;}