#![allow(unused_imports, unused_macros)] use kyoproio::*; use std::{ collections::*, io::{self, prelude::*}, iter, mem, }; fn run(mut kin: I, mut out: O) { let (n, m, t): (usize, usize, u64) = kin.input(); let mut a = vec![vec![false; n]; n]; for (u, v) in kin.iter::<(usize, usize)>().take(m) { a[u][v] = true; } let c = pow(a, t); let ans = c[0].iter().filter(|x| **x).count(); outln!(out, "{}", ans); } fn pow(mut a: Vec>, mut k: u64) -> Vec> { let n = a.len(); let mut c = id(n); while k > 0 { if k % 2 == 1 { c = mul(&c, &a); } a = mul(&a, &a); k /= 2; } c } fn mul(a: &[Vec], b: &[Vec]) -> Vec> { let n = a.len(); let mut c = vec![vec![false; n]; n]; for i in 0..n { for j in 0..n { for k in 0..n { c[i][j] |= a[i][k] & b[k][j]; } } } c } fn id(n: usize) -> Vec> { let mut c = vec![vec![false; n]; n]; for i in 0..n { c[i][i] = true; } c } // ----------------------------------------------------------------------------- fn main() -> io::Result<()> { std::thread::Builder::new() .stack_size(1 << 26) .spawn(|| { run( KInput::new(io::stdin().lock()), io::BufWriter::new(io::stdout().lock()), ) })? .join() .unwrap(); Ok(()) } #[macro_export] macro_rules! out { ($($arg:tt)*) => { write!($($arg)*).unwrap(); } } #[macro_export] macro_rules! outln { ($dst:expr $(, $($arg:tt)*)?) => {{ writeln!($dst $(, $($arg)*)?).unwrap(); if cfg!(debug_assertions) { $dst.flush().unwrap(); } }} } #[macro_export] macro_rules! eout { ($($arg:tt)*) => { if cfg!(debug_assertions) { eprintln!($($arg)*); } } } #[macro_export] macro_rules! kdbg { ($($v:expr),*) => { if cfg!(debug_assertions) { dbg!($($v),*) } else { ($($v),*) } } } pub mod kyoproio { use std::{ io::prelude::*, iter::FromIterator, marker::PhantomData, mem::{self, MaybeUninit}, str, }; pub trait Input { fn bytes(&mut self) -> &[u8]; fn str(&mut self) -> &str { str::from_utf8(self.bytes()).unwrap() } fn input(&mut self) -> T { T::input(self) } fn iter(&mut self) -> Iter { Iter(self, PhantomData) } fn collect>(&mut self, n: usize) -> B { self.iter().take(n).collect() } fn mapped U, B: FromIterator>( &mut self, n: usize, f: F, ) -> B { self.iter().take(n).map(f).collect() } } impl Input for &mut I { fn bytes(&mut self) -> &[u8] { (**self).bytes() } } pub struct KInput { src: R, buf: Vec, pos: usize, len: usize, } impl KInput { pub fn new(src: R) -> Self { Self { src, buf: vec![0; 1 << 16], pos: 0, len: 0, } } fn read(&mut self) -> usize { if self.pos > 0 { self.buf.copy_within(self.pos..self.len, 0); self.len -= self.pos; self.pos = 0; } else if self.len >= self.buf.len() { self.buf.resize(2 * self.buf.len(), 0); } let n = self.src.read(&mut self.buf[self.len..]).unwrap(); self.len += n; n } } impl Input for KInput { fn bytes(&mut self) -> &[u8] { loop { while let Some(d) = self.buf[self.pos..self.len] .iter() .position(u8::is_ascii_whitespace) { let p = self.pos; self.pos += d + 1; if d > 0 { return &self.buf[p..p + d]; } } if self.read() == 0 { return &self.buf[mem::replace(&mut self.pos, self.len)..self.len]; } } } } pub struct Iter<'a, T, I: ?Sized>(&'a mut I, PhantomData<*const T>); impl<'a, T: InputItem, I: Input + ?Sized> Iterator for Iter<'a, T, I> { type Item = T; fn next(&mut self) -> Option { Some(self.0.input()) } fn size_hint(&self) -> (usize, Option) { (!0, None) } } pub trait InputItem: Sized { fn input(src: &mut I) -> Self; } impl InputItem for Vec { fn input(src: &mut I) -> Self { src.bytes().to_owned() } } macro_rules! from_str { ($($T:ty)*) => {$( impl InputItem for $T { fn input(src: &mut I) -> Self { src.str().parse::<$T>().unwrap() } } )*} } from_str!(String char bool f32 f64); macro_rules! parse_int { ($($I:ty: $U:ty)*) => {$( impl InputItem for $I { fn input(src: &mut I) -> Self { let f = |s: &[u8]| s.iter().fold(0, |x, b| 10 * x + (b & 0xf) as $I); let s = src.bytes(); if let Some((&b'-', t)) = s.split_first() { -f(t) } else { f(s) } } } impl InputItem for $U { fn input(src: &mut I) -> Self { src.bytes().iter().fold(0, |x, b| 10 * x + (b & 0xf) as $U) } } )*} } parse_int!(isize:usize i8:u8 i16:u16 i32:u32 i64:u64 i128:u128); macro_rules! tuple { ($H:ident $($T:ident)*) => { impl<$H: InputItem, $($T: InputItem),*> InputItem for ($H, $($T),*) { fn input(src: &mut I) -> Self { ($H::input(src), $($T::input(src)),*) } } tuple!($($T)*); }; () => {} } tuple!(A B C D E F G); macro_rules! array { ($($N:literal)*) => {$( impl InputItem for [T; $N] { fn input(src: &mut I) -> Self { let mut arr = MaybeUninit::uninit(); let ptr = arr.as_mut_ptr() as *mut T; unsafe { for i in 0..$N { ptr.add(i).write(src.input()); } arr.assume_init() } } } )*} } array!(1 2 3 4 5 6 7 8); }