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nxt = head[u];head[u] = ejs;
e[++ejs].v = u;e[ejs].w = 0;e[ejs].nxt = head[v];head[v] = ejs;
}
int dep[N];
queue<int>q;
int S,T;
int low[N],rd[N],cd[N],ans,cur[N];
int bfs() {
memset(dep,0,sizeof(dep));
while(!q.empty()) q.pop();
dep[S] = 1;q.push(S);
while(!q.empty()) {
int u = q.front();q.pop();
for(int i = head[u];i;i = e[i].nxt) {
int v = e[i].v;
if(!dep[v] && e[i].w) {
q.push(v);
dep[v] = dep[u] + 1;
if(v == T) return 1;
}
}
}
return 0;
}
int dfs(int u,int now) {
if(u == T) return now;
int ret = 0;
for(int &i = cur[u];i;i = e[i].nxt) {
int v = e[i].v;
if(dep[v] == dep[u] + 1 && e[i].w) {
int k = dfs(v,min(now - ret,e[i].w));
e[i].w -= k;
e[i ^ 1].w += k;
ret += k;
if(now == ret) return ret;
}
}
return ret;
}
int dinic() {
int ans = 0;
while(bfs()) {
memcpy(cur,head,sizeof(cur));
ans += dfs(S,INF);
}
return ans;
}
int main() {
int n = read(),m = read();
int SS = read(),TT = read();
add(TT,SS,INF);
S = n + 1,T = S + 1;
for(int i = 1;i <= m;++i) {
int u = read(),v = read(),low = read(), up = read();
add(u,v,up - low);
rd[v] += low;
cd[u] += low;
}
for(int i = 1;i <= n;++i) {
int d = rd[i] - cd[i];
if(d > 0) ans += d,add(S,i,d);
if(d < 0) add(i,T,-d);
}
if(ans != dinic()) {
puts("please go home to sleep");
return 0;
}
for(int i = head[S];i;i = e[i].nxt)
e[i].w = e[i ^ 1].w = 0;
for(int i = head[T];i;i = e[i].nxt) e[i].w = e[i ^ 1].w = 0;
ans = e[3].w;
e[3].w = e[2].w = 0;
S = TT;T = SS;//!!!
ans -= dinic();//!!!
cout<<ans;
return 0;
}
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