//#pragma GCC optimize("Ofast,unroll-loops")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,fma,abm,mmx,avx,avx2,tune=native")
#include <bits/stdc++.h>
using namespace std;
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
#ifdef rd
#define trace(...) cout<<"Line:"<<__LINE__<<" "; __f(#__VA_ARGS__, __VA_ARGS__)
template<typename Arg1>
void __f(const char* name, Arg1&& arg1) {
	cout<<name<<" : "<<arg1<<endl;
}
template<typename Arg1, typename ... Args>
void __f(const char* names, Arg1&& arg1, Args&&... args) {
	const char* comma=strchr(names+1,',');
	cout.write(names,comma-names)<<" : "<<arg1<<" | ";
	__f(comma+1,args...);
}
#else
#define trace(...)
#define endl '\n'
#endif
#define pb push_back
#define fi first
#define se second
//#define int long long
typedef long long ll;
typedef long double f80;
#define double long double
#define pii pair<int,int>
#define pll pair<ll,ll>
#define sz(x) ((long long)x.size())
#define fr(a,b,c) for(int a=b; a<=c; a++)
#define rep(a,b,c) for(int a=b; a<c; a++)
#define trav(a,x) for(auto &a:x)
#define all(con) con.begin(),con.end()
const ll infl=2e18;
const int infi=1e9;
//const int mod=998244353;
const int mod=1000'000'007;
typedef vector<int> vi;
typedef tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update> oset;
auto clk=clock();
mt19937_64 rang(chrono::high_resolution_clock::now().time_since_epoch().count());
int rng(int lim) {
	uniform_int_distribution<int> uid(0,lim-1);
	return uid(rang);
}
#define MX (355)
#define EG (12505)
#define FOR(i, m, n) for (int i(m); i < n; i++)
#define F(n) FOR(i,0,n)
#define FF(n) FOR(j,0,n)
#define FT(m, n) FOR(k, m, n)
#define PB push_back
typedef pair<int,int> ii;
#define INF int(1e9+1)
#define aa first
#define bb second
struct MCMF{
    MCMF(){m=0;}
    void CLR(int N,int S,int T){
        m=0,n=N,s=S+1,t=T+1;
        F(n)g[i+1].clear();
    }
    void RST(){F(m)E[i].F=0;}
    void ade(int f,int t,int F,int C) {
        E[m++]=eg(++f,++t,0,F,C);
        E[m++]=eg(t,f,0,0,-C);
        g[f].PB(m-2);
        g[t].PB(m-1);
    }
    struct eg{
        int f,t,F,C,W;
        eg(int a=0,int b=0,int c=0,int d=0,int e=0){f=a,t=b,C=d,W=e,F=c;}
        inline int OT(int u){return f^t^u;}
    };
    bool C[MX];
    int n,m,s,t,p[MX],D[MX],P[MX];
    vi g[MX];
    eg E[2*EG];
    priority_queue<ii> Q;
    int BF(int u){
        if(C[u])return p[u];
        if(u==s)return p[s]=0;
        C[u]=1,p[u]=INF;
        for(auto h:g[u])if(E[h^1].F<E[h^1].C)
            p[u]=min(p[u],BF(E[h^1].OT(u))+E[h^1].W);
        return p[u];
    }
    bool DJ(){
        int u,OT,W;
        memset(C,0,n+1),fill(D+1,D+n+1,INF),D[s]=0;
        Q.push({0,s});
        while(!Q.empty()){
            u=Q.top().bb,Q.pop();
            if(C[u]++)continue;
            for(auto h:g[u]){
                OT=E[h].OT(u),W=E[h].W+p[u]-p[OT];
                if(E[h].F<E[h].C&&D[u]+W<D[OT])
                    D[OT]=D[u]+W,P[OT]=h,Q.push({-D[OT],OT});
            }
        }
        F(n)D[i+1]+=p[i+1]-p[s];
        return C[t];
    }
    ii mf(){
        memset(p,0,(n+1)<<2),BF(t);
        int F=0,W=0,u,X,S;
        while(DJ()){
            u=t,X=INF,S=0;
            while(u^s)
                X=min(X,E[P[u]].C-E[P[u]].F),
                S+=E[P[u]].W,u=E[P[u]].OT(u);
            u=t;
            while(u^s)
                E[P[u]].F+=X,E[P[u]^1].F-=X,
                u=E[P[u]].OT(u);
            F+=X,W+=X*S;
            memcpy(p,D,(n+1)<<2);
        }
        return {F,W};
    }
}G;


void solve() {
	int n,m,s,d;
	cin>>n>>m>>s>>d;
	while(m--) {
		int x,y,c,z;
		cin>>x>>y>>c>>z;
		G.ade(x, y, c, z);
	}
	cout<<G.mf().second<<endl;

}

signed main() {
	ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0);
	srand(chrono::high_resolution_clock::now().time_since_epoch().count());
	cout<<fixed<<setprecision(10);
	freopen("fmcm.in","r",stdin);
	freopen("fmcm.out","w",stdin);
	int t=1;
//	cin>>t;
	while(t--)
		solve();
#ifdef rd
	cout<<endl<<endl<<endl<<endl<<"Time elapsed: "<<(double)(clock()-clk)/CLOCKS_PER_SEC<<endl;
#endif
	return 0;
}