#include <cstdio>
#include <fstream>
#include <cstring>

using namespace std;

FILE *fin = fopen("nunta.in", "r");
FILE *fout = fopen("nunta.out", "w");

int n, i, j, t;
int A[200], B[200], C[200];

int main(){
    fscanf(fin, "%d", &n);
    if(n == 1){
        fprintf(fout, "1");
    } else {
        A[0] = B[0] = A[1] = B[1] = 1;
        for(i = 1; i < n; i++){
            t = 0;
            for(j = 1; j <= A[0] || j <= B[0] || t; j++){
                t += A[j] + B[j];
                C[j] = t % 10;
                t /= 10;
            }
            C[0] = j - 1;
            memcpy(A, B, sizeof(B));
            memcpy(B, C, sizeof(C));
        }
        for(i = C[0]; i > 0; i--){
            fprintf(fout, "%d", C[i]);
        }
    }
    return 0;
}