use num::{One, Zero};
use proconio::input;
type ModInt = modint::ModInt<modint::M1000000007>;

fn main() {
    input!(s: usize);

    let mut dp = vec![ModInt::zero(); s + 1];
    dp[0] = ModInt::one();
    for i in 3..=s {
        dp[i] = dp[i - 1] + dp[i - 3];
    }
    let ans = dp[s];

    println!("{}", ans);
}

#[allow(dead_code)]
mod modint {
    //! For the modular arithmetic.

    use num::{
        self,
        integer::Integer,
        traits::{Inv, Num, One, Pow, Zero},
    };
    use std::{
        cell::RefCell,
        convert::Infallible,
        fmt,
        iter::{Product, Sum},
        marker::PhantomData,
        ops::{
            Add, AddAssign, Div, DivAssign, Mul, MulAssign, Neg, Rem, RemAssign, Sub, SubAssign,
        },
        str::FromStr,
        thread::LocalKey,
    };

    #[derive(Copy, Clone, Eq, PartialEq, Hash)]
    #[repr(transparent)]
    pub struct ModInt<M>(u32, PhantomData<fn() -> M>);

    impl<M: Modulus> ModInt<M> {
        pub fn new<V: ModU32>(val: V) -> Self { val.into() }
        pub fn modulus() -> u32 { M::modulus() }
        pub fn val(self) -> u32 { self.0 }
        /// # Safety
        /// `val` must be less than `modulus`
        pub unsafe fn raw(val: u32) -> Self { Self(val, PhantomData) }
    }

    impl<M: Modulus> Default for ModInt<M> {
        fn default() -> Self { Self::zero() }
    }

    impl<M: Modulus, V: ModU32> From<V> for ModInt<M> {
        fn from(val: V) -> Self { unsafe { Self::raw(val.mod_u32(Self::modulus())) } }
    }

    impl<M: Modulus> FromStr for ModInt<M> {
        type Err = Infallible;
        fn from_str(src: &str) -> Result<Self, Infallible> { Self::from_str_radix(src, 10) }
    }

    impl<M: Modulus> fmt::Display for ModInt<M> {
        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
            fmt::Display::fmt(&self.val(), f)
        }
    }
    impl<M: Modulus> fmt::Debug for ModInt<M> {
        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { fmt::Debug::fmt(&self.val(), f) }
    }

    impl<M: Modulus> Zero for ModInt<M> {
        fn zero() -> Self { unsafe { Self::raw(0) } }
        fn is_zero(&self) -> bool { self.0 == 0 }
    }
    impl<M: Modulus> One for ModInt<M> {
        fn one() -> Self { unsafe { Self::raw(1) } }
    }

    impl<M: Modulus> Neg for ModInt<M> {
        type Output = Self;
        fn neg(self) -> Self { Self::zero() - self }
    }
    impl<M: Modulus> Inv for ModInt<M> {
        type Output = Self;
        fn inv(self) -> Self {
            assert_ne!(self.0, 0, "attempt to get inverse of zero");
            let e = i64::extended_gcd(&self.0.into(), &M::modulus().into());
            assert_ne!(e.gcd, 1, "multiplicative inverse does not exist");
            Self::from(e.x)
        }
    }

    impl<M: Modulus> Add for ModInt<M> {
        type Output = Self;
        fn add(self, rhs: Self) -> Self {
            let m = M::modulus();
            let val = self.0 + rhs.0;
            unsafe { Self::raw(if val >= m { val - m } else { val }) }
        }
    }
    impl<M: Modulus> Sub for ModInt<M> {
        type Output = Self;
        fn sub(self, rhs: Self) -> Self {
            let m = M::modulus();
            let val = self.0.wrapping_sub(rhs.0);
            unsafe { Self::raw(if val >= m { val.wrapping_add(m) } else { val }) }
        }
    }
    impl<M: Modulus> Mul for ModInt<M> {
        type Output = Self;
        fn mul(self, rhs: Self) -> Self {
            unsafe { Self::raw((self.0 as u64 * rhs.0 as u64 % M::modulus() as u64) as u32) }
        }
    }
    #[allow(clippy::suspicious_arithmetic_impl)]
    impl<M: Modulus> Div for ModInt<M> {
        type Output = Self;
        fn div(self, rhs: Self) -> Self { self * rhs.inv() }
    }
    /// always return zero, unless `rhs == 0`.
    impl<M: Modulus> Rem for ModInt<M> {
        type Output = Self;
        fn rem(self, rhs: Self) -> Self {
            assert_ne!(rhs.0, 0, "attempt to divide by zero");
            Self::zero()
        }
    }
    macro_rules! forward_ref_binop {
        ($trait:ident, $op:ident) => {
            impl<'a, M: Modulus> $trait<ModInt<M>> for &'a ModInt<M> {
                type Output = ModInt<M>;
                fn $op(self, rhs: ModInt<M>) -> ModInt<M> { (*self).$op(rhs) }
            }
            impl<M: Modulus> $trait<&ModInt<M>> for ModInt<M> {
                type Output = ModInt<M>;
                fn $op(self, rhs: &ModInt<M>) -> ModInt<M> { self.$op(*rhs) }
            }
            impl<M: Modulus> $trait<&ModInt<M>> for &ModInt<M> {
                type Output = ModInt<M>;
                fn $op(self, rhs: &ModInt<M>) -> ModInt<M> { self.$op(*rhs) }
            }
        };
    }
    forward_ref_binop!(Add, add);
    forward_ref_binop!(Sub, sub);
    forward_ref_binop!(Mul, mul);
    forward_ref_binop!(Div, div);
    forward_ref_binop!(Rem, rem);

    macro_rules! binop_assign {
        ($assign_trait:ident, $assign:ident, $op:ident) => {
            impl<M: Modulus> $assign_trait for ModInt<M> {
                fn $assign(&mut self, rhs: Self) { *self = self.$op(rhs) }
            }
        };
    }
    binop_assign!(AddAssign, add_assign, add);
    binop_assign!(SubAssign, sub_assign, sub);
    binop_assign!(MulAssign, mul_assign, mul);
    binop_assign!(DivAssign, div_assign, div);
    binop_assign!(RemAssign, rem_assign, rem);
    macro_rules! forward_ref_op_assign {
        ($trait:ident, $op:ident) => {
            impl<M: Modulus> $trait<&ModInt<M>> for ModInt<M> {
                #[inline]
                fn $op(&mut self, rhs: &ModInt<M>) { self.$op(*rhs) }
            }
        };
    }
    forward_ref_op_assign!(AddAssign, add_assign);
    forward_ref_op_assign!(SubAssign, sub_assign);
    forward_ref_op_assign!(MulAssign, mul_assign);
    forward_ref_op_assign!(DivAssign, div_assign);
    forward_ref_op_assign!(RemAssign, rem_assign);

    impl<M: Modulus> Num for ModInt<M> {
        type FromStrRadixErr = Infallible;
        fn from_str_radix(src: &str, radix: u32) -> Result<Self, Infallible> {
            assert!(2 <= radix && radix <= 36, "radix must be in `[2, 36]`");
            assert!(!src.is_empty(), "attempt to parse empty str");
            let src = src.as_bytes();
            let (positive, digits) = match src[0] {
                b'+' => (true, &src[1..]),
                b'-' => (false, &src[1..]),
                _ => (true, src),
            };
            assert!(!digits.is_empty(), "attempt to parse sign");
            let mut result = 0_u64;
            for &c in digits {
                let x = (c as char).to_digit(radix).expect("found invalid char") as u64;
                result = (result * 10 + x) % M::modulus() as u64;
            }
            let ret = unsafe { Self::raw(result as u32) };
            Ok(if positive { ret } else { -ret })
        }
    }

    impl<M: Modulus> Pow<u64> for ModInt<M> {
        type Output = Self;
        fn pow(mut self, mut exp: u64) -> Self {
            let mut acc = Self::one();
            while exp > 0 {
                if exp & 1 == 1 {
                    acc *= self;
                }
                self *= self;
                exp >>= 1;
            }
            acc
        }
    }

    impl<M: Modulus> Sum for ModInt<M> {
        fn sum<I: Iterator<Item = Self>>(iter: I) -> Self {
            iter.fold(Self::zero(), |acc, x| acc + x)
        }
    }
    impl<'a, M: Modulus> Sum<&'a Self> for ModInt<M> {
        fn sum<I: Iterator<Item = &'a Self>>(iter: I) -> Self {
            iter.fold(Self::zero(), |acc, x| acc + *x)
        }
    }
    impl<M: Modulus> Product for ModInt<M> {
        fn product<I: Iterator<Item = Self>>(iter: I) -> Self {
            iter.fold(Self::zero(), |acc, x| acc + x)
        }
    }
    impl<'a, M: Modulus> Product<&'a Self> for ModInt<M> {
        fn product<I: Iterator<Item = &'a Self>>(iter: I) -> Self {
            iter.fold(Self::zero(), |acc, x| acc + *x)
        }
    }

    pub trait Modulus: 'static + Copy + Eq {
        fn modulus() -> u32;
    }

    #[macro_export]
    macro_rules! static_modulus {
        (type $type:ident : u32 = $val:expr) => {
            #[derive(Copy, Clone, Ord, PartialOrd, Eq, PartialEq, Hash, Debug)]
            pub enum $type {}
            impl Modulus for $type {
                fn modulus() -> u32 { $val }
            }
        };
    }
    static_modulus!(type M998244353: u32 = 998_244_353);
    static_modulus!(type M1000000007: u32 = 1_000_000_007);

    /// default modulus is `998_244_353`
    #[derive(Copy, Clone, Ord, PartialOrd, Eq, PartialEq, Hash, Debug)]
    pub enum DynamicModulus {}
    impl DynamicModulus {
        pub fn set(modulus: u32) {
            assert_ne!(modulus, 0, "modulus must not be 0");
            Self::value_key().with(|val| *val.borrow_mut() = modulus)
        }
        fn value_key() -> &'static LocalKey<RefCell<u32>> {
            thread_local!(static MOD: RefCell<u32> = RefCell::new(998_244_353));
            &MOD
        }
    }
    impl Modulus for DynamicModulus {
        fn modulus() -> u32 { Self::value_key().with(|val| *val.borrow()) }
    }

    pub trait ModU32 {
        fn mod_u32(self, rhs: u32) -> u32;
    }
    macro_rules! mod_u32_for_small {
        ($($type:ty),*) => {$(
            impl ModU32 for $type {
                fn mod_u32(self, rhs:u32) -> u32 {
                        (self as i128).rem_euclid(rhs as i128) as u32
                    }
                }
        )*};
    }
    macro_rules! mod_u32_for_large {
        ($($type:ty),*) => {$(
            impl ModU32 for $type {
                fn mod_u32(self, rhs:u32) -> u32 {
                    self.rem_euclid(rhs as $type) as u32
                }
            }
        )*};
    }
    mod_u32_for_small!(i8, i16, i32, i64, i128, isize, u8, u16, u32, u64);
    mod_u32_for_large!(u128);
    #[cfg(target_pointer_width = "32")]
    mod_u32_for_small!(usize);
    #[cfg(target_pointer_width = "64")]
    mod_u32_for_small!(usize);
}


Measured memory_bytes: 2112