Go: package main

/*
フィボナッチ数列
*/

import (
	"bufio"
	"bytes"
	"fmt"
	"log"
	"os"
	"strconv"
	"strings"
)

func fibWithMemo(n int, memo map[int]int) int {
	if n == 0 || n == 1 {
		return 1
	}
	if val, ok := memo[n]; ok {
		return val
	}
	memo[n] = fibWithMemo(n-1, memo) + fibWithMemo(n-2, memo)
	return memo[n]
}

func fib(n int) int {
	memo := make(map[int]int)
	return fibWithMemo(n, memo)
}

func main() {
	scanner := makeScanner(1024)
	n := eGetInt(scanner)
	fmt.Println(fib(n))
}

////////////////////////////////////////////////////////////////////////////////
// ライブラリ
////////////////////////////////////////////////////////////////////////////////
func makeScanner(maxByte int) *bufio.Scanner {
	scanner := bufio.NewScanner(os.Stdin)
	scanner.Buffer(make([]uint8, 0, 8192), maxByte)
	return scanner
}
func makeWordScanner() *bufio.Scanner {
	scanner := makeScanner(8192)
	scanner.Split(bufio.ScanWords)
	return scanner
}
func eGetLine(r *bufio.Scanner) string {
	if r.Scan() {
		return r.Text()
	}
	err := r.Err()
	if err != nil {
		log.Fatal(err)
	}
	// EOF
	return ""
}
func eGetInt(r *bufio.Scanner) int {
	line := eGetLine(r)
	return eAtoi(line)
}
func eGetFields(r *bufio.Scanner) []string {
	line := eGetLine(r)
	return strings.Fields(line)
}
func eGetInts(r *bufio.Scanner) []int {
	fields := eGetFields(r)
	ints := make([]int, len(fields))
	for i := 0; i < len(ints); i++ {
		ints[i] = eAtoi(fields[i])
	}
	return ints
}
func eGetChars(r *bufio.Scanner) []string {
	line := eGetLine(r)
	return strings.Split(line, "")
}
func eAtoi(s string) int {
	n, err := strconv.Atoi(s)
	if err != nil {
		log.Fatal(err)
	}
	return n
}

type ints []int

func (s ints) String() string {
	var buf bytes.Buffer
	buf.WriteString("[")
	sep := ""
	for _, v := range s {
		buf.WriteString(fmt.Sprintf("%s%d", sep, v))
		sep = ", "
	}
	buf.WriteString("]")
	return buf.String()
}

func reverse(a ints) ints {
	r := make(ints, len(a))
	for i := 0; i < len(a); i++ {
		r[i] = a[len(a)-1-i]
	}
	return r
}
func max(a ints) (int, bool) {
	if len(a) == 0 {
		return 0, false
	}
	m := a[0]
	for _, e := range a {
		if e > m {
			m = e
		}
	}
	return m, true
}
func min(a []int) int {
	m := a[0]
	for _, v := range a {
		if v < m {
			m = v
		}
	}
	return m
}

func sum(a ints) int {
	if len(a) == 0 {
		return 0
	}
	sum := 0
	for _, e := range a {
		sum += e
	}
	return sum
}
func find(n int, a ints) int {
	for i, v := range a {
		if n == v {
			return i
		}
	}
	return -1
}

C++: #include <algorithm>
#include <bitset>
#include <cassert>
#include <cctype>
#include <cmath>
#include <cstdlib>
#include <functional>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <set>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;

#define IOS ios::sync_with_stdio(false); cin.tie(0);
#define FOR(i, s, n) for(int i = s, i##_len=(n); i < i##_len; ++i)
#define FORS(i, s, n) for(int i = s, i##_len=(n); i <= i##_len; ++i)
#define VFOR(i, s, n) for(int i = s; i < (n); ++i)
#define VFORS(i, s, n) for(int i = s; i <= (n); ++i)
#define REP(i, n) FOR(i, 0, n)
#define REPS(i, n) FORS(i, 0, n)
#define VREP(i, n) VFOR(i, 0, n)
#define VREPS(i, n) VFORS(i, 0, n)
#define RFOR(i, s, n) for(int i = s, i##_len=(n); i >= i##_len; --i)
#define RFORS(i, s, n) for(int i = s, i##_len=(n); i > i##_len; --i)
#define RREP(i, n) RFOR(i, n, 0)
#define RREPS(i, n) RFORS(i, n, 0)
#define ALL(v) (v).begin(), (v).end()
#define SORT(v) sort(ALL(v))
#define RSORT(v) sort(ALL(v), greater<decltype(v[0])>())
#define SZ(x) ((int)(x).size())
#define PB push_back
#define MP make_pair
#define MT make_tuple
#define BIT(n) (1LL<<(n))
#define UNIQUE(v) v.erase(unique(ALL(v)), v.end());

using ll = long long;
using PII = pair<int, int>;
using VI = vector<int>;
using VD = vector<double>;
using VLL = vector<ll>;
using VS = vector<string>;

const int MOD = 1000000007;
const int INF = 1000000000;

template<class T> bool chmax(T &a, const T &b){
    if(a < b){
        a = b; return true;
    }
    return false;
}
template<class T> bool chmin(T &a, const T &b){
    if(b < a){
        a = b; return true;
    }
    return false;
}



template <class T>
class Matrix{
private:
    vector<vector<T>> A;
public:
    Matrix(){}

    Matrix(size_t m, size_t n): A(m, vector<T>(n, 0)) {}

    Matrix(size_t n): A(n, vector<T>(n, 0)) {}

    Matrix(size_t m, size_t n, T a): A(m, vector<T>(n, a)) {}

    Matrix(const Matrix& mat){if(this != &mat) A = mat.A;}

    Matrix(vector<vector<T>> v){
        size_t m = v.size();
        assert(m != 0);
        size_t  n = v[0].size();
        REP(i, m) assert(v[i].size() == n);
        A = v;
    }

    ~Matrix() {}

    size_t height() const{return A.size();}

    size_t width() const{return A[0].size();}

    bool sameSize(const Matrix& mat) const{
        return height() == mat.height() && width() == mat.width();
    }

    inline const vector<T> &operator[](int idx) const{return A.at(idx);}

    inline vector<T> &operator[](int k){return (A.at(k));}

    void print2D(int w){
        size_t m = height(), n = width();
        REP(i, m){
            REP(j, n){
                if(j) cout << " ";
                cout << setw(w) << (*this)[i][j];
            }
            cout << "\n";
        }
    }

    friend ostream& operator<<(ostream &os, const Matrix &mat){
        size_t m = mat.height(), n = mat.width();
        REP(i, m){
            REP(j, n){
                if(j) os << " ";
                os << mat[i][j];
            }
            os << "\n";
        }
        return (os);
    }

    static Matrix identity(size_t n){
        Matrix ret(n);
        REP(i, n) ret[i][i] = 1;
        return ret;
    }

    Matrix operator+() const{return *this;}

    Matrix operator-() const{
        size_t m = height(), n = width();
        Matrix temp(height(), width());
        REP(i, m) REP(j, n) temp[i][j] = -(*this)[i][j];
        return temp;
    }

    Matrix& operator=(const Matrix mat){
        if(this != &mat){
            A = mat.A;
        }
        return *this;
    }

    Matrix& operator+=(const Matrix &B){
        size_t m = height(), n = width();
        assert(m == B.height() && n == B.width());
        REP(i, m) REP(j, n) (*this)[i][j] += B[i][j];
        return *this;
    }

    Matrix& operator-=(const Matrix &B){
        size_t m = height(), n = width();
        assert(m == B.height() && n == B.width());
        REP(i, m) REP(j, n) (*this)[i][j] -= B[i][j];
        return *this;
    }

    Matrix& operator*=(const Matrix &B){
        size_t m = height(), n = width(), l = B.width();
        assert(n == B.height());
        vector<vector<T>> C(m, vector<T>(l, 0));
        REP(i, m) REP(j, l) REP(k, n)
            C[i][j] = (C[i][j] + (*this)[i][k] * B[k][j]);
        A.swap(C);
        return *this;
    }

    Matrix& operator%=(const ll &mod){
        size_t m = height(), n = width();
        REP(i, m) REP(j, n) (*this)[i][j] %= mod;
        return *this;
    }

    Matrix operator+(const Matrix& mat) const{
        Matrix temp(*this);
        return temp += mat;
    }

    Matrix operator-(const Matrix& mat) const{
        Matrix temp(*this);
        return temp -= mat;
    }

    Matrix operator*(const Matrix& mat) const{
        Matrix temp(*this);
        return temp *= mat;
    }

    Matrix operator%(const ll mod) const{
        Matrix temp(*this);
        return temp %= mod;
    }

    bool operator==(const Matrix& mat) const{
        if(!sameSize(mat)) return false;
        size_t m = height(), n = width();
        REP(i, m) REP(j, n) if((*this)[i][j] != mat[i][j]) return false;
        return true;
    }

    bool operator!=(const Matrix& mat) const{return !(*this == mat);}
    
    Matrix powWithoutMod(ll b){
        size_t n = height();
        assert(n == width());
        Matrix ret = identity(n);
        Matrix a = *this;
        while(b){
            if(b & 1) ret = ret * a;
            a = a * a;
            b /= 2;
        }
        return ret;
    }

    Matrix pow(ll b, ll mod){
        size_t n = height();
        assert(n == width());
        Matrix ret = identity(n);
        Matrix a = *this;
        while(b){
            if(b & 1) ret = (ret * a) % mod;
            a = (a * a) % mod;
            b /= 2;
        }
        return ret;
    }

    Matrix pow(ll b) {
        return pow(b, MOD);
    }
};

ll fibonacci(int n){
    if(!n) return 1;
    vector<ll> a1{1, 1}, a2{1, 0};
    vector<vector<ll>> a{a1, a2};
    Matrix<ll> mat(a);
    mat = mat.powWithoutMod(n-1);
    return mat[0][0] + mat[0][1];
}

int main(){
    int n; cin >> n;
    cout << fibonacci(n) << "\n";
    return 0;
}