macro_rules ! input { ( source = $ s : expr , $ ( $ r : tt ) * ) => { let mut iter = $ s . split_whitespace ( ) ; input_inner ! { iter , $ ( $ r ) * } } ; ( iter = $ iter : ident , $ ( $ 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 ) * } } ; ( $ ( $ 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_rules ! input_inner { ( $ iter : expr ) => { } ; ( $ iter : expr , ) => { } ; ( $ iter : expr , mut $ var : ident : $ t : tt $ ( $ r : tt ) * ) => { let mut $ var = read_value ! ( $ iter , $ t ) ; input_inner ! { $ iter $ ( $ r ) * } } ; ( $ iter : expr , mut $ var : ident $ ( $ r : tt ) * ) => { input_inner ! { $ iter , mut $ var : usize $ ( $ r ) * } } ; ( $ iter : expr , $ var : ident : $ t : tt $ ( $ r : tt ) * ) => { let $ var = read_value ! ( $ iter , $ t ) ; input_inner ! { $ iter $ ( $ r ) * } } ; ( $ iter : expr , $ var : ident $ ( $ r : tt ) * ) => { input_inner ! { $ iter , $ var : usize $ ( $ r ) * } } ; }
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 : $ base : expr } ) => { read_value ! ( $ iter , String ) . chars ( ) . map ( | c | ( c as u8 - $ base as u8 ) as usize ) . collect ::< Vec < usize >> ( ) } ; ( $ iter : expr , { char : $ base : expr } ) => { read_value ! ( $ iter , { chars : $ base } ) [ 0 ] } ; ( $ iter : expr , chars ) => { read_value ! ( $ iter , String ) . chars ( ) . collect ::< Vec < char >> ( ) } ; ( $ iter : expr , char ) => { read_value ! ( $ iter , chars ) [ 0 ] } ; ( $ iter : expr , usize1 ) => { read_value ! ( $ iter , usize ) - 1 } ; ( $ iter : expr , $ t : ty ) => { $ iter . next ( ) . unwrap ( ) . parse ::<$ t > ( ) . unwrap ( ) } ; }
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub struct Adjacent {
    pub to: usize,
    pub id: usize,
}
impl Adjacent {
    pub fn new(to: usize, id: usize) -> Adjacent {
        Adjacent { to: to, id: id }
    }
}
#[derive(Clone, Debug, Default)]
pub struct Graph {
    pub vsize: usize,
    pub esize: usize,
    pub graph: Vec<Vec<Adjacent>>,
}
impl Graph {
    pub fn new(vsize: usize) -> Graph {
        Graph {
            vsize: vsize,
            esize: 0,
            graph: vec![vec![]; vsize],
        }
    }
    pub fn add_edge(&mut self, from: usize, to: usize) {
        self.graph[from].push(Adjacent::new(to, self.esize));
        self.esize += 1;
    }
    pub fn add_undirected_edge(&mut self, u: usize, v: usize) {
        self.graph[u].push(Adjacent::new(v, self.esize));
        self.graph[v].push(Adjacent::new(u, self.esize));
        self.esize += 1;
    }
    pub fn vertexes(&self) -> std::ops::Range<usize> {
        0..self.vsize
    }
    pub fn adjacency(&self, from: usize) -> &Vec<Adjacent> {
        &self.graph[from]
    }
}
#[derive(Debug)]
pub struct TreeRec {
    pub n: usize,
    pub xmax: usize,
    pub dp: Vec<Vec<usize>>,
    pub c: Vec<usize>,
    pub x: Vec<usize>,
    pub ans: bool,
}
const INF: usize = 1_001_001_001;
use std::cmp::min;
impl TreeRec {
    pub fn new(n: usize, x: Vec<usize>) -> TreeRec {
        let xmax = *x.iter().max().unwrap();
        TreeRec {
            n: n,
            xmax: xmax,
            dp: vec![vec![INF; xmax + 1]; n + 1],
            c: vec![INF; n],
            x: x,
            ans: true,
        }
    }
    pub fn dfs(&mut self, u: usize, p: usize, graph: &Graph) {
        let a = self.x[u];
        let xmax = self.xmax;
        self.dp[u][0] = 0;
        for v in graph.adjacency(u) {
            if v.to != p {
                self.dfs(v.to, u, graph);
                let mut tmp = vec![INF; xmax + 1];
                let (y, z) = (self.x[v.to], self.c[v.to]);
                for i in 0..xmax + 1 {
                    let d = self.dp[u][i];
                    if d < INF {
                        if i + y <= xmax {
                            tmp[i + y] = min(tmp[i + y], d + z);
                        }
                        if i + z <= xmax {
                            tmp[i + z] = min(tmp[i + z], d + y);
                        }
                    }
                }
                self.dp[u] = tmp;
            }
        }
        for i in 0..a + 1 {
            let m = min(self.c[u], self.dp[u][i]);
            self.c[u] = m;
        }
        if self.c[u] >= INF {
            self.ans = false;
        }
    }
}
fn main() {
    input! { n, p: [usize1; n-1], x: [usize; n] };
    let mut g = Graph::new(n);
    let mut r = TreeRec::new(n, x);
    for i in 0..n - 1 {
        g.add_undirected_edge(p[i], i + 1);
    }
    r.dfs(0, n, &g);
    println!("{}", if r.ans { "POSSIBLE" } else { "IMPOSSIBLE" });
}


Measured memory_bytes: 56600