#include <cstdio>
#include <cstring>
#define LMAX 220
typedef unsigned char Huge[LMAX];
inline void Copy(Huge &A,Huge &B){
    for(int i=0;i<=B[0];++i)
        A[i]=B[i];
};
inline void Set(Huge &A){
    int siz=A[0];
    for(int i=0;i<=siz;++i)
        A[i]=0;
}
inline void Atrib(Huge &A,int x){
    Set(A);
    if(!x) A[++A[0]]=0;
    while(x){
        A[++A[0]]=x%10;
        x/=10;
    }
}
inline void SumMare(Huge A,Huge B,Huge &C){
    Set(C);
    int i,r=0;
    for(i=1;i<=A[0]||i<=B[0]||r;++i){
        int aux=r+A[i]+B[i];
        C[i]=aux%10;
        r=aux/10;
    }
    C[0]=i-1;
}
inline void Write(Huge A){
    for(int i=A[0];i;--i)
        printf("%d",A[i]);
    printf("\n");
}
Huge A,B,C;
int main(){
    freopen("nunta.in","r",stdin);
    freopen("nunta.out","w",stdout);
    Atrib(A,1);Atrib(B,1);
    int n;
    scanf("%d",&n);
    for(int i=2;i<=n;++i){
        SumMare(A,B,C);
        Copy(A,B);
        Copy(B,C);
    }
    Write(B);
    return 0;
}