#include <iostream>
#include <string>
#include <ctime>

using namespace std;

#define buffsz 65536
#define MM 16505
#define NM 355
#define inf 2000000000

int vec[MM], cst[MM], start[NM], stop[NM], gi[NM];
int N, M, S, D;

FILE *fin;

char buff[buffsz];
int unde, refuri;

int C[NM][NM], F[NM][NM];

long long fmcm;

inline void refresh()
{
    int hm = fread (buff, 1, buffsz, fin);   
    if (hm < buffsz) buff[hm] = 0;
    unde = 0;
    ++refuri;
}

inline int cifra(char ch)
{
     if(ch >= '0' && ch <= '9') return 1;
     return 0;  
}

inline int semn(char ch)
{
     if(ch == '-') return 1;
     return 0;  
}

int readnr()
{
    int ans = 0, minus = 0;
    
    one:
        while ((unde < buffsz) && (!cifra(buff[unde])) && (!semn(buff[unde])) ) ++unde;
        if (unde == buffsz)
        {
             refresh();
             goto one;     
        }
    
    if (semn(buff[unde]))
    {
        minus = 1;
        ++unde;                
    }    
    
    two:
        while ((unde < buffsz) && (cifra(buff[unde])))
        {
             ans = ans*10 + buff[unde] - '0';
             ++unde; 
        }
        if (unde == buffsz)
        {
             refresh();
             goto two;    
        }
     
    if (minus) ans *= (-1);
    
    return ans;   
}

int BLF()
{
    int DMIN[NM], FAT[NM], CD[5*NM];
    bool IN[NM];
    
    for (int i = 0; i <= N; ++i)
    {
        DMIN[i] = inf;
        FAT[i] = 0;
        IN[i] = 0;
    }
    
    int st = 0, dr = 0;
    
    DMIN[S] = 0;
    CD[st] = S;
    IN[S] = 1;
    
    while(st <= dr)
    {
        int nod = CD[st%NM];     
        IN[nod] = 0;
        ++st;
        
        if (IN[FAT[nod]]) continue;
        
        for (int i = start[nod]; i <= stop[nod]; ++i)
        {
            int nnod = vec[i];
            int cost = cst[i];
            
            if (C[nod][nnod] - F[nod][nnod] <= 0) continue;
            
            if (DMIN[nnod] > DMIN[nod] + cost)
            {
                 DMIN[nnod] = DMIN[nod] + cost;
                 FAT[nnod] = nod;
                 
                 if (!IN[nnod])
                 {
                     ++dr;
                     CD[dr%NM] = nnod;
                     IN[nnod] = 1;
                 }          
            }
        }
    }
    
    if (DMIN[D] == inf) return 0;
    
    int fc = inf;
    
    int nod = D;
    
    while (FAT[nod])
    {
         int fat = FAT[nod]; 
         
         fc = min (fc, C[fat][nod] - F[fat][nod]);
         
         nod = fat;
    } 
    
    fmcm += (long long) fc * DMIN[D];
    
    nod = D;
    
    while (FAT[nod])
    {
         int fat = FAT[nod]; 
         
         F[fat][nod] += fc;
         F[nod][fat] -= fc;
         
         nod = fat;
    } 
    
    return 1;
}

int main()
{
    int clk_start=clock();
    
    int a, b, c, d;
    
    //freopen ("fmcm.in", "r", stdin);
    freopen ("fmcm.out", "w", stdout);
    
    //annoying stuff
    
    fin = fopen ("fmcm.in", "r");
    
    refresh();
    
    N = readnr();
    M = readnr();
    S = readnr();
    D = readnr();
    
    for (int i = 1; i <= M; ++i)
    {
         a = readnr();
         b = readnr();
         c = readnr();
         d = readnr();
         
         ++gi[a];
         ++gi[b];   
    }
    
    fclose(fin);
    
    int unde_bagi = 1;
    
    for (int i = 1; i <= N; ++i)
    {
        start[i] = unde_bagi;
        
        unde_bagi += gi[i];
        
        stop[i] = unde_bagi-1;
    }
    
    memset (gi, 0, sizeof(gi));
    
    fin = fopen ("fmcm.in", "r");
    
    refresh();
    
    N = readnr();
    M = readnr();
    S = readnr();
    D = readnr();
    
    for (int i = 1; i <= M; ++i)
    {
         a = readnr();
         b = readnr();
         c = readnr();
         d = readnr();
         
         C[a][b]+=c;
         
         int unde_a = start[a] + gi[a];
         int unde_b = start[b] + gi[b];
         
         vec[unde_a] = b;
         cst[unde_a] = d;
         
         vec[unde_b] = a;
         cst[unde_b] = -d;
         
         ++gi[a];
         ++gi[b];   
    }
    
    fclose(fin);
    
    /*
    for (int i = 1; i <= N; ++i)
    {
        printf ("%d-->", i);
        
        for (int j = start[i]; j <= stop[i]; ++j) printf ("%d ", vec[j]);
        
        printf ("\n");
    }
    */
    
    while(BLF());
    
    printf ("%lld", fmcm);
    
    int clk_stop=clock();
    
    //printf ("\n%lf", (double)(clk_stop-clk_start)/CLOCKS_PER_SEC);
    
    return 0;
}