#include<cstdio>
#include<cstring>
int n,i,t,a[210],b[210],c[210];
int main() {
    freopen("nunta1.txt","r",stdin),freopen("nunta2.txt","w",stdout),scanf("%d",&n);
    if(n<3)
        printf("%d",n);
    else {
        a[0]=b[0]=a[1]=b[1]=1;
        for(;n>1;n--) {
            for(c[0]=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,memcpy(a,b,sizeof(b)),memcpy(b,c,sizeof(c));
        }
        for(i=c[0];i;i--)
            printf("%d",c[i]);
    }
    fclose(stdin),fclose(stdout);
    return 0;
}