// 有向
// 全体が強連結な時
// 二部グラフじゃないならok
// 強連結じゃないなら？
// 全部通るパスが存在するかつ最後以外については内部でokにできる
//
// Kが使えてないが？

fn main() {
    input! {
        n: usize,
        m: usize,
        _k: usize,
        e: [(usize1, usize1); m],
    }
    let ans = if solve(n, e) {"Yes"} else {"No"};
    println!("{ans}");
}

fn solve(n: usize, e: Vec<(usize, usize)>) -> bool {
    let mut g = vec![vec![]; n];
    for &(s, t) in e.iter() {
        g[s].push(t);
    }
    let (len, id) = strongly_connected_components(n, |v| g[v].iter().cloned());
    if id[0] != 0 {
        return false;
    }
    let mut topo = vec![vec![]; len];
    let mut deg = vec![0; len];
    let mut dsu = DSU::new(2 * n);
    for &(s, t) in e.iter() {
        let a = id[s];
        let b = id[t];
        if a == b {
            dsu.unite(s, t + n);
            dsu.unite(t, s + n);
        } else {
            topo[a].push(b);
            deg[b] += 1;
        }
    }
    if deg.iter().filter(|d| **d == 0).count() > 1 {
        return false;
    }
    let mut v = deg.iter().rposition(|d| *d == 0).unwrap();
    for i in 0..len {
        if v != i {
            return false;
        }
        for &u in topo[i].iter() {
            deg[u] -= 1;
            if deg[u] == 0 {
                v = v.max(u);
            }
        }
    }
    let mut size = vec![0; len];
    let mut ok = false;
    for i in 0..n {
        let a = id[i];
        size[a] += 1;
        if a + 1 < len {
            if !dsu.same(a, a + n) {
                return false;
            }
        } else {
            ok |= dsu.same(a, a + n);
        }
    }
    ok || size[len - 1] == 1
}

// ---------- begin input macro ----------
// reference: https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
#[macro_export]
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

#[macro_export]
macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};
    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };
}

#[macro_export]
macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };
    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };
    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };
    ($iter:expr, bytes) => {
        read_value!($iter, String).bytes().collect::<Vec<u8>>()
    };
    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };
    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}
// ---------- end input macro ----------
// ---------- begin scc ----------
pub fn strongly_connected_components<G, I>(size: usize, graph: G) -> (usize, Vec<usize>)
where
    G: Fn(usize) -> I,
    I: Iterator<Item = usize>,
{
    let mut ord = vec![0; size];
    let mut res = vec![0; size];
    let mut vertex = vec![];
    let mut dfs = vec![];
    let mut id = 0;
    for s in 0..size {
        if ord[s] > 0 {
            continue;
        }
        vertex.push(s);
        ord[s] = vertex.len();
        dfs.push((s, graph(s)));
        while let Some((v, mut it)) = dfs.pop() {
            if let Some(u) = it.find(|u| ord[*u] == 0) {
                vertex.push(u);
                ord[u] = vertex.len();
                dfs.extend([(v, it), (u, graph(u))]);
            } else {
                let low = graph(v).map(|u| ord[u]).min().unwrap_or(ord[v]);
                if low < ord[v] {
                    ord[v] = low;
                    continue;
                }
                let s = vertex.iter().rposition(|u| *u == v).unwrap();
                for u in vertex.drain(s..) {
                    ord[u] = !0;
                    res[u] = id;
                }
                id += 1;
            }
        }
    }
    res.iter_mut().for_each(|p| *p = id - 1 - *p);
    (id, res)
}
// ---------- end scc ----------

//---------- begin union_find ----------
pub struct DSU {
    p: Vec<i32>,
}
impl DSU {
    pub fn new(n: usize) -> DSU {
        assert!(n < std::i32::MAX as usize);
        DSU { p: vec![-1; n] }
    }
    pub fn init(&mut self) {
        self.p.iter_mut().for_each(|p| *p = -1);
    }
    pub fn root(&self, mut x: usize) -> usize {
        assert!(x < self.p.len());
        while self.p[x] >= 0 {
            x = self.p[x] as usize;
        }
        x
    }
    pub fn same(&self, x: usize, y: usize) -> bool {
        assert!(x < self.p.len() && y < self.p.len());
        self.root(x) == self.root(y)
    }
    pub fn unite(&mut self, x: usize, y: usize) -> Option<(usize, usize)> {
        assert!(x < self.p.len() && y < self.p.len());
        let mut x = self.root(x);
        let mut y = self.root(y);
        if x == y {
            return None;
        }
        if self.p[x] > self.p[y] {
            std::mem::swap(&mut x, &mut y);
        }
        self.p[x] += self.p[y];
        self.p[y] = x as i32;
        Some((x, y))
    }
    pub fn parent(&self, x: usize) -> Option<usize> {
        assert!(x < self.p.len());
        let p = self.p[x];
        if p >= 0 {
            Some(p as usize)
        } else {
            None
        }
    }
    pub fn sum<F>(&self, mut x: usize, mut f: F) -> usize
    where
        F: FnMut(usize),
    {
        while let Some(p) = self.parent(x) {
            f(x);
            x = p;
        }
        x
    }
    pub fn size(&self, x: usize) -> usize {
        assert!(x < self.p.len());
        let r = self.root(x);
        (-self.p[r]) as usize
    }
}
//---------- end union_find ----------