#![allow(non_snake_case)]
use std::collections::BinaryHeap;
use proconio::{input};

fn main() {
    input!{
        n: usize, m: usize, x: u64,
        es: [(usize, usize, u64, u64); m]
    }
    let mut adj = vec![Vec::new(); n];
    for (u, v, c, t) in es {
        adj[u - 1].push((v - 1, c + t * x));
        adj[v - 1].push((u - 1, c + t * x));
    }
    let mut dist = vec![u64::MAX; n];
    dist[0] = 0;
    let mut pq = BinaryHeap::new();
    pq.push((0, 0));
    while let Some((d, u)) = pq.pop() {
        if (-d) as u64 > dist[u] { continue; }
        for (v, c) in &adj[u] {
            let d1 = (-d) as u64 + c;
            if d1 < dist[*v] {
                dist[*v] = d1;
                pq.push((-(d1 as i64), *v));
            }
        }
    }

    if dist[n - 1] == u64::MAX {
        println!("-1");
    } else {
        println!("{}", (dist[n - 1] + x - 1) / x);
    }
}