#include<cstdio>
#include<cstring>
int n,i,A[100],B[100],C[100],t;
int main() {
    FILE *fin=fopen("nunta.in","r"),*fout=fopen("nunta.out","w");
    fscanf(fin,"%d",&n);
    if(n==1)
        fprintf(fout, "1");
    else {
        A[0]=B[0]=A[1]=B[1]=1;
        for(;n>1;n--) {
            for(t=0,i=1;i<=A[0]||i<=B[0]||t;i++)
                t+=A[i]+B[i],C[i]=t%10,t/=10;
            C[0]=i-1,memcpy(A,B,sizeof(B)),memcpy(B,C,sizeof(C));
        }
        for(i=C[0];i;i--)
            fprintf(fout,"%d",C[i]);
    }
}