import java.math.BigInteger;
import java.util.Scanner;
class Fib {

        static BigInteger calcSlow(int n) {
                if (n <= 1)
                        return n == 0 ? BigInteger.ZERO : BigInteger.ONE;
                BigInteger f0 = BigInteger.ZERO, f1 = BigInteger.ONE, f2;
                for (int i = 0; i < n - 1; i++) {
                        f2 = f0.add(f1);
                        f0 = f1;
                        f1 = f2;
                }
                return f1;
        }

        static int calcMod(int n, long MOD) {
                Matrix m = new Matrix(2);
                m.a[0][0] = m.a[0][1] = m.a[1][0] = 1;
                return (int) Matrix.powMod(m, n, MOD).a[0][1];
        }

        static class Matrix {
                int n;
                long[][] a;

                Matrix(int n) {
                        this.n = n;
                        this.a = new long[n][n];
                }

                static Matrix multiply(Matrix m1, Matrix m2, long MOD) {
                        int n = m1.n;
                        Matrix ret = new Matrix(n);
                        for (int i = 0; i < n; i++) {
                                for (int j = 0; j < n; j++) {
                                        for (int t = 0; t < n; t++) {
                                                ret.a[i][j] += m1.a[i][t] * m2.a[t][j];
                                                ret.a[i][j] %= MOD;
                                        }
                                }
                        }
                        return ret;
                }

                static Matrix id(int n) {
                        Matrix ret = new Matrix(n);
                        for (int i = 0; i < n; i++)
                                ret.a[i][i] = 1;
                        return ret;
                }

                // evaluates matr^n modulo MOD
                static Matrix powMod(Matrix matr, int n, long MOD) {
                        if (n == 0)
                                return id(2);
                        Matrix t = Matrix.powMod(matr, n / 2, MOD);
                        t = Matrix.multiply(t, t, MOD);
                        return n % 2 == 0 ? t : Matrix.multiply(t, matr, MOD);
                }
        }
        public static void main(String[] args) {
        int n = new Scanner(System.in).nextInt();
        System.out.println(calcSlow(n));
    }
}