1 #include<bits/stdc++.h>
2 #define rep(i,x,y) for (int i=(x);i<=(y);i++)
3 #define ll long long
4 #define inf 1000000001
5 #define y1 y1___
6 using namespace std;
7 char gc(){
8 static char buf[100000],*p1=buf,*p2=buf;
9 return p1==p2&&(p2=(p1=buf)+fread(buf,1,100000,stdin),p1==p2)?EOF:*p1++;
10 }
11 #define gc getchar
12 ll read(){
13 char ch=gc();ll x=0;int op=1;
14 for (;!isdigit(ch);ch=gc()) if (ch=='-') op=-1;
15 for (;isdigit(ch);ch=gc()) x=(x<<1)+(x<<3)+ch-'0';
16 return x*op;
17 }
18 #define N 205
19 #define M 9999+N<<1
20 int n,m,cnt=1,s_,t_,s,t,head[N],d[N],vis[N],cur[N];
21 struct edge{int to,nxt,c;}e[M];
22 void adde(int x,int y,int c){
23 e[++cnt].to=y;e[cnt].nxt=head[x];head[x]=cnt;
24 e[cnt].c=c;//d：原图下界；c：新图容量
25 }
26 void ins(int x,int y,int z){
27 adde(x,y,z);adde(y,x,0);
28 }
29 bool bfs(){
30 queue<int> q;q.push(s);
31 rep (i,1,t) vis[i]=-1;vis[s]=1;
32 while (!q.empty()){
33 int u=q.front();q.pop();
34 for (int i=head[u];i;i=e[i].nxt){
35 int v=e[i].to;
36 if (e[i].c&&vis[v]==-1) vis[v]=vis[u]+1,q.push(v);
37 }
38 }
39 return vis[t]!=-1;
40 }
41 int dfs(int u,int flow){
42 if (u==t) return flow;
43 int w,used=0;
44 for (int &i=cur[u];i;i=e[i].nxt){
45 int v=e[i].to;
46 if (e[i].c&&vis[v]==vis[u]+1){
47 w=dfs(v,min(flow-used,e[i].c));
48 e[i].c-=w,e[i^1].c+=w,used+=w;
49 if (used==flow) return used;
50 }
51 }
52 if (!used) vis[u]=-1;
53 return used;
54 }
55 int dinic(){
56 int ret=0;
57 while (bfs()){
58 memcpy(cur,head,sizeof(cur));//当前弧优化
59 ret+=dfs(s,inf);
60 }
61 return ret;
62 }
63 void del(int u){
64 for (int &i=head[u];i&&e[i].to>n;i=e[i].nxt);
65 }
66 int main(){
67 n=read(),m=read(),s_=read(),t_=read();
68 rep (i,1,m){
69 int x=read(),y=read(),a=read(),b=read();
70 ins(x,y,b-a);d[x]-=a,d[y]+=a;
71 }
72 s=n+1,t=n+2;
73 rep (i,1,n) if (d[i]>0) ins(s,i,d[i]);else ins(i,t,-d[i]);
74 ins(t_,s_,inf);//转化为无源汇问题
75 dinic();
76 for (int i=head[s];i;i=e[i].nxt) if (vis[e[i].to]!=-1) return puts("please go home to sleep"),0;//判无解
77 head[s]=head[t]=0;
78 rep (i,1,n) del(i);//删去i连向t的边
79 s=s_,t=t_;
80 printf("%d
",dinic());
81 return 0;
82 }
