#![allow(unused)] use kyoproio::*; use std::{ collections::*, io::{self, prelude::*}, iter, mem::{replace, swap}, }; fn main() -> io::Result<()> { std::thread::Builder::new() .stack_size(50 * 1024 * 1024) .spawn(solve)? .join() .unwrap(); Ok(()) } fn solve() { let stdin = io::stdin(); let mut kin = Input::new(stdin.lock()); let stdout = io::stdout(); let mut out = io::BufWriter::new(stdout.lock()); macro_rules! output { ($($args:expr),+) => { write!(&mut out, $($args),+) }; } macro_rules! outputln { ($($args:expr),+) => { output!($($args),+); outputln!() }; () => { output!("\n"); if cfg!(debug_assertions) { out.flush(); } } } const MOD: i64 = 1e9 as i64 + 7; let [n, d, k]: [usize; 3] = kin.input(); let mut dp = vec![0; d * n + 1]; dp[0] = 1; let mut dp_next = Vec::new(); for _ in 0..n { dp_next.clear(); dp_next.resize(dp.len(), 0); for i in 0..dp.len() - d { for j in 1..=d { dp_next[i + j] += dp[i]; dp_next[i + j] %= MOD; } } swap(&mut dp, &mut dp_next); } outputln!("{}", dp[k]); } // ----------------------------------------------------------------------------- pub mod kyoproio { #![warn(unused)] pub use std::io::prelude::*; pub struct Input { src: R, buf: String, pos: usize, } impl Input { pub fn new(src: R) -> Self { Self { src, buf: String::with_capacity(1024), pos: 0, } } pub fn str(&mut self) -> &str { loop { if self.pos >= self.buf.len() { self.buf.clear(); let len = self.src.read_line(&mut self.buf).expect("io error"); self.pos = 0; if len == 0 { return &self.buf; } } let range = self.pos ..self.buf[self.pos..] .find(|c: char| c.is_ascii_whitespace()) .map(|i| i + self.pos) .unwrap_or_else(|| self.buf.len()); self.pos = range.end + 1; if range.end - range.start > 0 { return &self.buf[range]; } } } pub fn bytes(&mut self) -> &[u8] { self.str().as_ref() } pub fn input(&mut self) -> T { self.input_fallible().expect("input error") } pub fn input_fallible(&mut self) -> Result { T::input(self) } pub fn iter(&mut self) -> Iter { Iter { input: self, _t: std::marker::PhantomData, } } } pub struct Iter<'a, T, R> { input: &'a mut Input, _t: std::marker::PhantomData, } impl<'a, T: InputParse, R: BufRead> Iterator for Iter<'a, T, R> { type Item = T; fn next(&mut self) -> Option { Some(self.input.input()) } } type Result = std::result::Result>; pub trait InputParse: Sized { fn input(input: &mut Input) -> Result; } macro_rules! input_from_str_impls { { $($T:ty)* } => { $(impl InputParse for $T { fn input(input: &mut Input) -> Result { input.str().parse::<$T>().map_err(|e| e.into()) } })* }; } macro_rules! input_tuple_impls { { $(($($T:ident),+))* } => { $(impl<$($T: InputParse),+> InputParse for ($($T),+) { fn input(input: &mut Input) -> Result { Ok(($($T::input(input)?),+)) } })* }; } macro_rules! input_array_impls { { $($N:expr)* } => { $(impl InputParse for [T; $N] { fn input(input: &mut Input) -> Result { use std::{ mem::MaybeUninit, ptr }; let mut a = MaybeUninit::<[T; $N]>::uninit(); unsafe { for i in 0..$N { match T::input(input) { Ok(v) => ptr::write(&mut (*a.as_mut_ptr())[i], v), Err(e) => { ptr::drop_in_place(&mut (*a.as_mut_ptr())[..i]); return Err(e); } } } Ok(a.assume_init()) } } })* }; } input_from_str_impls! { String char bool f32 f64 isize i8 i16 i32 i64 i128 usize u8 u16 u32 u64 u128 } input_tuple_impls! { (A, B) (A, B, C) (A, B, C, D) (A, B, C, D, E) (A, B, C, D, E, F) (A, B, C, D, E, F, G) } input_array_impls! { 1 2 3 4 5 6 7 8 } }