use std::io::*;

fn dfs(v: usize, p: usize, g: &Vec<Vec<usize>>) -> (usize, usize) {
    let mut res = (v, 0);
    for &nv in g[v].iter() {
        if nv != p {
            let mut tmp = dfs(nv, v, g);
            tmp.1 += 1;
            if tmp.1 > res.1 {
                res = tmp;
            }
        }
    }
    res
}

fn calc_dep(v: usize, p: usize, d: usize, dep: &mut Vec<usize>, g: &Vec<Vec<usize>>) {
    dep[v] = d;
    for &nv in g[v].iter() {
        if nv != p {
            calc_dep(nv, v, d + 1, dep, g);
        }
    }
}

fn main() {
    let mut s: String = String::new();
    std::io::stdin().read_to_string(&mut s).ok();
    let mut itr = s.trim().split_whitespace();
    let n: usize = itr.next().unwrap().parse().unwrap();
    let mut g: Vec<Vec<usize>> = vec![Vec::new(); n];
    let mut deg: Vec<usize> = vec![0; n];
    for _ in 0..n - 1 {
        let a: usize = itr.next().unwrap().parse::<usize>().unwrap() - 1;
        let b: usize = itr.next().unwrap().parse::<usize>().unwrap() - 1;
        deg[a] += 1;
        deg[b] += 1;
        g[a].push(b);
        g[b].push(a);
    }
    let mut leaf = Vec::new();
    let res1 = dfs(0, 0, &g);
    let res2 = dfs(res1.0, n, &g);

    for i in 0..n {
        if deg[i] == 1 {
            leaf.push(i);
        }
    }

    let mut dep = vec![0; n];
    calc_dep(res1.0, n, 0, &mut dep, &g);
    let mut ok = true;
    dep[res1.0] = res2.1;
    for i in 1..leaf.len() {
        ok &= dep[leaf[i]] == dep[leaf[0]];
    }
    calc_dep(res2.0, n, 0, &mut dep, &g);
    dep[res2.0] = res2.1;
    for i in 1..leaf.len() {
        ok &= dep[leaf[i]] == dep[leaf[0]];
    }
    if ok {
        println!("Yes")
    } else {
        println!("No")
    }
}