#include<cstdio>
#include<cstring>
char A[200],B[200],C[200];
short i,t,n;
int main() {
    freopen("nunta.in","r",stdin),freopen("nunta.out","w",stdout),scanf("%hd",&n);
    A[0]=B[0]=C[0]=A[1]=B[1]=C[1]=1;
    for(;n>1;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,memcpy(A,B,sizeof(B)),memcpy(B,C,sizeof(C));
    }
    for(i=C[0];i;i--)
        printf("%hd",C[i]);
}