#![allow(non_snake_case)]

use std::io::{ self, prelude::* };

macro_rules! pick {
    ($tokens:expr) => {
        $tokens.next().unwrap().parse().expect("parse error")
    }
}

fn main() {
    let mut s = String::new();
    io::stdin().read_to_string(&mut s).expect("i/o error");
    let mut tokens = s.split_whitespace();

    let N: usize = pick!(tokens);
    let mut A: Vec<u64> = Vec::with_capacity(N-1);
    for _ in 0..N-1 {
        A.push(pick!(tokens));
    }
    let mut B: Vec<u64> = Vec::with_capacity(N);
    let mut C: Vec<u64> = Vec::with_capacity(N);
    for _ in 0..N {
        B.push(pick!(tokens));
        C.push(pick!(tokens));
    }

    let mut k = 0;
    let mut ans = 0;
    for i in 0..N-1 {
        k -= B[i];
        k += C[i];
        ans += k * A[i];
    }

    println!("{}", ans);
}