最大流
#ifdef ONLINE_JUDGE
#else
#define Qiu_Cheng
#endif
#include <bits/stdc++.h>
#define int long long
using namespace std;
// typedef long long ll;
const int N=1e5+5,mod=1e9+7,inf=INT_MAX;
// const int mod1=469762049,mod2=998244353,mod3=1004535809;
// const int G=3,Gi=332748118;
// const int M=mod1*mod2;
inline int read()
{int x=0,f=1;char c=getchar();while(c<'0'||c>'9'){if(c=='-'){f=-1;}c=getchar();}while(c>='0'&&c<='9'){x=(x<<3)+(x<<1)+(c-'0');c=getchar();}return x*f;
}
inline void write(int x)
{if(x<0){putchar('-');x=-x;}if(x>9) write(x/10);putchar(x%10+'0');
}
int n,m;
int pos[N],dep[N];
int l[N],r[N],cha[N];
struct node{int to,c,lp;};
vector<node>g[N];
void add(int from,int to,int c)
{g[from].push_back((node){to,c,(int)g[to].size()});g[to].push_back((node){from,0,(int)g[from].size()-1});
}
void fc(int s)
{memset(dep,-1,sizeof(dep));dep[s]=0;queue<int>q;q.push(s);while(!q.empty()){int u=q.front();q.pop();for(auto v:g[u]){if(v.c>0&&dep[v.to]<0){dep[v.to]=dep[u]+1;q.push(v.to);}}}
}
int dfs(int u,int t,int f)
{if(u==t||!f) return f;int ans=0;for(int &i=pos[u];i<g[u].size();i++){auto &x=g[u][i];if(x.c>0&&dep[x.to]==dep[u]+1){int frz=dfs(x.to,t,min(f,x.c));if(frz>0){x.c-=frz;g[x.to][x.lp].c+=frz;f-=frz;ans+=frz;if(!f)break;}}}return ans;
}
int max_flow=0;
int dinic(int s,int t)
{int flow=0;while(1){fc(s);if(dep[t]==-1) return flow;memset(pos,0,sizeof(pos));flow+=dfs(s,t,inf);}
}
int ss,tt,S,T;
inline void solve()
{cin>>n>>m>>ss>>tt;S=0,T=n+2;for(int i=1;i<=m;i++){int x,y;cin>>x>>y>>l[i]>>r[i];add(x,y,r[i]-l[i]);cha[x]-=l[i],cha[y]+=l[i];}int cnt=0;for(int i=1;i<=n;i++){if(cha[i]>0) add(S,i,cha[i]),cnt+=cha[i];else if(cha[i]<0) add(i,T,-cha[i]);}int zky=g[ss].size();add(tt,ss,mod);if(dinic(S,T)!=cnt){cout<<"No Solution"<<endl;return;}else{max_flow+=g[ss][zky].c;g[ss][g[ss].size()-1].c=0;g[tt][g[tt].size()-1].c=0;// g[s].erase(g[s].begin()+g[s].size(),g[s].begin()+g[s].size()+1);// g[t].erase(g[t].begin()+g[t].size(),g[t].begin()+g[t].size()+1);max_flow+=dinic(ss,tt);cout<<max_flow<<endl;}
}
signed main()
{
#ifdef Qiu_Cheng freopen("1.in","r",stdin); freopen("1.out","w",stdout);
#endif // ios::sync_with_stdio(false); // cin.tie(0); cout.tie(0); // int QwQ; // cin>>QwQ; // while(QwQ--)solve(); solve(); return 0;
}
//12 825076913 0 173167432
// 6666 66666 666666
// 6 6 6 6 6
// 6 6 6666 6
// 6 6 6 6 6
// 6666 6 6 6666666//g++ -O2 -std=c++14 -Wall "-Wl,--stack= 536870912 " cao.cpp -o cao.exe
最小流
#ifdef ONLINE_JUDGE
#else
#define Qiu_Cheng
#endif
#include <bits/stdc++.h>
#define int long long
using namespace std;
// typedef long long ll;
const int N=5e5+5,mod=1e9+7,inf=1e18;
// const int mod1=469762049,mod2=998244353,mod3=1004535809;
// const int G=3,Gi=332748118;
// const int M=mod1*mod2;
inline int read()
{int x=0,f=1;char c=getchar();while(c<'0'||c>'9'){if(c=='-'){f=-1;}c=getchar();}while(c>='0'&&c<='9'){x=(x<<3)+(x<<1)+(c-'0');c=getchar();}return x*f;
}
inline void write(int x)
{if(x<0){putchar('-');x=-x;}if(x>9) write(x/10);putchar(x%10+'0');
}
int n,m;
int pos[N],dep[N];
int l[N],r[N],cha[N];
struct node{int to,c,lp;};
vector<node>g[N];
void add(int from,int to,int c)
{g[from].push_back((node){to,c,(int)g[to].size()});g[to].push_back((node){from,0,(int)g[from].size()-1});
}
void fc(int s)
{memset(dep,-1,sizeof(dep));dep[s]=0;queue<int>q;q.push(s);while(!q.empty()){int u=q.front();q.pop();for(auto v:g[u]){if(v.c>0&&dep[v.to]<0){dep[v.to]=dep[u]+1;q.push(v.to);}}}
}
int dfs(int u,int t,int f)
{if(u==t||!f) return f;int ans=0;for(int &i=pos[u];i<g[u].size();i++){auto &x=g[u][i];if(x.c>0&&dep[x.to]==dep[u]+1){int frz=dfs(x.to,t,min(f,x.c));if(frz>0){x.c-=frz;g[x.to][x.lp].c+=frz;f-=frz;ans+=frz;if(!f)break;}}}return ans;
}
int max_flow=0;
int dinic(int s,int t)
{int flow=0;while(1){fc(s);if(dep[t]==-1) return flow;memset(pos,0,sizeof(pos));flow+=dfs(s,t,inf);}
}
int ss,tt,S,T;
inline void solve()
{cin>>n>>m>>ss>>tt;S=0,T=n+2;for(int i=1;i<=m;i++){int x,y;cin>>x>>y>>l[i]>>r[i];add(x,y,r[i]-l[i]);cha[x]-=l[i],cha[y]+=l[i];}int cnt=0;for(int i=1;i<=n;i++){if(cha[i]>0) add(S,i,cha[i]),cnt+=cha[i];else if(cha[i]<0) add(i,T,-cha[i]);}int zky=g[ss].size();add(tt,ss,inf);if(dinic(S,T)!=cnt){cout<<"No Solution"<<endl;return;}else{max_flow+=g[ss][zky].c;g[ss][g[ss].size()-1].c=0;g[tt][g[tt].size()-1].c=0;// g[s].erase(g[s].begin()+g[s].size(),g[s].begin()+g[s].size()+1);// g[t].erase(g[t].begin()+g[t].size(),g[t].begin()+g[t].size()+1);max_flow-=dinic(tt,ss);cout<<max_flow<<endl;}
}
signed main()
{
#ifdef Qiu_Cheng freopen("1.in","r",stdin); freopen("1.out","w",stdout);
#endif // ios::sync_with_stdio(false); // cin.tie(0); cout.tie(0); // int QwQ; // cin>>QwQ; // while(QwQ--)solve(); solve(); return 0;
}
//12 825076913 0 173167432
// 6666 66666 666666
// 6 6 6 6 6
// 6 6 6666 6
// 6 6 6 6 6
// 6666 6 6 6666666//g++ -O2 -std=c++14 -Wall "-Wl,--stack= 536870912 " cao.cpp -o cao.exe
