//ac

#include <iostream>
#include <vector>
using namespace std;

#define see(n) cout << #n << " = " << n << endl
#define seeArray(n, a) cout << #a << " = ";\
for (int __i__ = 0; __i__ < n; ++__i__)\
	cout << a[__i__] << " ";\
	cout << endl;
#define seeArray2(n, m, a) cout << #a << " = " << endl;\
for (int __i__ = 0; __i__ < n; ++__i__) {\
	for (int __j__ = 0; __j__ < m; ++__j__)\
		cout << a[__i__][__j__] << " ";\
			cout << endl;\
}

#define MAXN 205
#define inf 1000000000

int max_flow(int n,int mat[][MAXN],int source,int sink,int flow[][MAXN]){
	int pre[MAXN],que[MAXN],d[MAXN],p,q,t,i,j;
	if (source==sink) return inf;
	for (i=0;i<n;i++)
		for (j=0;j<n;flow[i][j++]=0);
	for (;;){
		for (i=0;i<n;pre[i++]=0);
		pre[t=source]=source+1,d[t]=inf;
		for (p=q=0;p<=q&&!pre[sink];t=que[p++])
			for (i=0;i<n;i++)
				if (!pre[i]&&(j=mat[t][i]-flow[t][i]))
					pre[que[q++]=i]=t+1,d[i]=d[t]<j?d[t]:j;
				else if (!pre[i]&&(j=flow[i][t]))
					pre[que[q++]=i]=-t-1,d[i]=d[t]<j?d[t]:j;
		if (!pre[sink]) break;
		for (i=sink;i!=source;)
			if (pre[i]>0)
				flow[pre[i]-1][i]+=d[sink],i=pre[i]-1;
			else
				flow[i][-pre[i]-1]-=d[sink],i=-pre[i]-1;
	}
	for (j=i=0;i<n;j+=flow[source][i++]);
	return j;
}

int n, m;
int mat[MAXN][MAXN], flow[MAXN][MAXN];
int ll[MAXN][MAXN];
int inner[MAXN], outer[MAXN];

void run() {
	cin >> n >> m;
	memset(mat, 0, sizeof(mat));
	memset(ll, 0, sizeof(ll));
	vector<pair<int, int> > mm;
	int s = n, t = n + 1;
	for (int i = 0; i < m; ++i) {
		int u, v, l, c;
		cin >> u >> v >> l >> c;
		--u, --v;
		mat[s][v] += l, mat[u][t] += l;
		mat[u][v] = c - l;
		ll[u][v] = l;
		mm.push_back(make_pair(u, v));
	}
	max_flow(n + 2, mat, s, t, flow);
	for (int i = 0; i < n; ++i) {
		if (flow[s][i] != mat[s][i] || flow[i][t] != mat[i][t]) {
			cout << "NO" << endl;
			return;
		}
	}
	cout << "YES" << endl;
	for (int i = 0; i < mm.size(); ++i) {
		int u = mm[i].first, v = mm[i].second;
		cout << flow[u][v] + ll[u][v]<< endl;
	}
}

int main() {
	run();
	return 0;
}