#include <cstdio>
#include <cstring>
#include <iostream>
#include <queue>
using namespace std;
const int N = 2e2 + 5, M = 2e4 + 5, INF = 1e9;
int n, m, s, t, w[N], ans[M];

int idx = 1, h[N];
struct edge 
{
    int to, nxt, val;
} e[M << 1];
void addEdge(int u, int v, int c) 
{
    e[++idx] = (edge) 
    {
        v, h[u], c
    };
    h[u] = idx;
}

int dep[N], now[N];
queue <int> q;
bool BFS() 
{
    memset(dep, 0, sizeof(dep));

    while (!q.empty())
        q.pop();

    dep[s] = 1, q.push(s);
    now[s] = h[s];

    while (!q.empty()) 
    {
        int u = q.front();
        q.pop();

        for (int i = h[u]; i; i = e[i].nxt) 
        {
            int v = e[i].to;

            if (!e[i].val || dep[v])
                continue;

            q.push(v), dep[v] = dep[u] + 1, now[v] = h[v];

            if (v == t)
                return true;
        }
    }

    return false;
}
int DFS(int u, int sum) 
{
    if (u == t)
        return sum;

    int res = 0;

    for (int &i = now[u]; i && sum; i = e[i].nxt) 
    {
        int v = e[i].to;

        if (dep[v] != dep[u] + 1 || !e[i].val)
            continue;

        int k = DFS(v, min(sum, e[i].val));
        e[i].val -= k, e[i ^ 1].val += k;
        ans[i >> 1] += ((i & 1) ? -1 : 1) * k;
        sum -= k, res += k;
    }

    return res;
}
bool dinic() 
{
    bool flag = true;

    while (BFS())
        DFS(s, INF);

    for (int i = (m << 1) + 2; i <= idx; i += 2)
        flag &= !e[i].val;

    return flag;
}

int main() 
{
    scanf("%d%d", &n, &m), t = n + 1;

    for (int i = 1, u, v, l, r; i <= m; i++)
        scanf("%d%d%d%d", &u, &v, &l, &r), w[u] -= l, w[v] += l, ans[i] = l, addEdge(u, v, r - l), addEdge(v, u, 0);

    for (int i = 1; i <= n; i++)
        if (w[i] > 0)
            addEdge(s, i, w[i]), addEdge(i, s, 0);
        else if (w[i] < 0)
            addEdge(i, t, -w[i]), addEdge(t, i, 0);

    if (!dinic())
        return puts("NO") & 0;

    puts("YES");

    for (int i = 1; i <= m; i++)
        printf("%d\n", ans[i]);

    return puts("") & 0;
}