1 #include <cstdio>
2 #include <cstring>
3 #include <queue>
4 using namespace std;
5 const int maxn = 210,maxm = 20800,inf = 1000000000;
6 int cnt = 1,ss,tt,n,m;
7 int head[maxn],dis[maxn],d[maxn],nxt[maxm],to[maxm],flow[maxm],low[maxm];
8 bool inq[maxn];
9 void add(int a,int b,int fl)
10 {
11 nxt[++cnt] = head[a];
12 to[cnt] = b;
13 head[a] = cnt;
14 flow[cnt] = fl;
15 nxt[++cnt] = head[b];
16 to[cnt] = a;
17 head[b] = cnt;
18 flow[cnt] = 0;
19 }
20
21 bool bfs()
22 {
23 queue <int> que;
24 memset(inq,0,sizeof(inq));
25 que.push(tt);
26 inq[tt] = 1;
27 while (!que.empty())
28 {
29 int cur = que.front();
30 que.pop();
31 for (int i = head[cur];i;i = nxt[i])
32 {
33 int v = to[i];
34 if (!inq[v] && flow[i ^ 1])
35 {
36 dis[v] = dis[cur] + 1;
37 que.push(v);
38 inq[v] = 1;
39 }
40 }
41 }
42 return inq[ss];
43 }
44 int dfs(int cur,int lmt)
45 {
46 if (cur == tt) return lmt;
47 int fl = 0;
48 for (int i = head[cur];i && fl < lmt;i = nxt[i])
49 {
50 if (dis[to[i]] + 1 == dis[cur] && flow[i])
51 {
52 int tt = dfs(to[i],min(lmt - fl,flow[i]));
53 flow[i] -= tt;
54 flow[i ^ 1] += tt;
55 fl += tt;
56 }
57 }
58 return fl;
59 }
60 int maxflow()
61 {
62 int res = 0;
63 while (bfs())
64 {
65 int fl = 0;
66 do
67 {
68 fl = dfs(ss,inf);
69 res += fl;
70 } while (fl);
71 }
72 return res;
73 }
74 //cnt = 1
75 int main()
76 {
77 scanf("%d%d",&n,&m);
78 ss = n + 1;
79 tt = n + 2;
80 int tx,ty,tl,tu;
81 for (int i = 1;i <= m;i++)
82 {
83 scanf("%d%d%d%d",&tx,&ty,&tl,&tu);
84 add(tx,ty,tu - tl);
85 d[tx] -= tl;
86 d[ty] += tl;
87 low[i] = tl;
88 }
89 int sum = 0;
90 for (int i = 1;i <= n;i++)
91 if (d[i] > 0)
92 {
93 sum += d[i];
94 add(ss,i,d[i]);
95 }else if (d[i] < 0)
96 add(i,tt,-d[i]);
97 if (maxflow() != sum)
98 {
99 printf("NO\n");
100 return 0;
101 }else
102 {
103 printf("YES\n");
104 for (int i = 1;i <= m;i++)
105 printf("%d\n",flow[i * 2 | 1] + low[i]);
106 }
107 return 0;
108 }
