#include <bits/stdc++.h>
//#pragma GCC optimize ("03")
#define FastIO ios_base::sync_with_stdio(false) , cin.tie(0) , cout.tie(0)
#define FILES freopen("fmcm.in" , "r" , stdin) , freopen("fmcm.out" , "w" , stdout)
#define ll long long
#define ull unsigned long long
#define ld long double
#define eb emplace_back
#define pb push_back
#define qwerty1 first
#define qwerty2 second
#define qwerty3 -> first
#define qwerty4 -> second
#define umap unordered_map
#define uset unordered_set
#define pii pair < int , short >

namespace FastRead
{
    char __buff[5000];short __lg = 0 , __p = 0;
    char nc()
    {
        if(__lg == __p){__lg = fread(__buff , 1 , 5000 , stdin);__p = 0;if(!__lg) return EOF;}
        return __buff[__p++];
    }
    template<class T>void read(T&__x)
    {
        T __sgn = 1; char __c;while(!isdigit(__c = nc()))if(__c == '-')__sgn = -1;
        __x = __c - '0';while(isdigit(__c = nc()))__x = __x * 10 + __c - '0';__x *= __sgn;
    }
}

using namespace FastRead;
using namespace std;

const short N = 355;

short n , m , x , y , c , z , sink , source;
vector < short > G[N];
int cost[N][N], dist[N] , d[N];
short parent[N] , capacity[N][N];
bool inq[N];
queue < short > q;

pii pq[N];
short pos[N];
short cnt = 0;

void HeapUp(short p)
{
    while(p > 1 && pq[p] < pq[p / 2])
    {
        swap(pos[pq[p].second] , pos[pq[p / 2].second]);
        swap(pq[p] , pq[p / 2]);
        p /= 2;
    }
}

void HeapDown(short p)
{
    bool ok = 0;

    do
    {
        ok = 0;
        short sw = 0;

        if(p * 2 <= cnt)
            sw = p * 2;

        if(p * 2 + 1 <= cnt)
            if(pq[p * 2] > pq[p * 2 + 1])
                sw = p * 2 + 1;

        if(sw && pq[p] > pq[sw])
        {
            swap(pos[pq[p].second] , pos[pq[sw].second]);
            swap(pq[p] , pq[sw]);
            p = sw;
            ok = 1;
        }
    }while(ok);
}

void insert(pii x)
{
    if(pos[x.second])
    {
        pq[pos[x.second]] = x;
        HeapDown(pos[x.second]);
        HeapUp(pos[x.second]);
    }
    else
    {
        pq[++cnt] = x;
        pos[x.second] = cnt;
        HeapUp(cnt);
    }
}

void pop()
{
    pos[pq[1].second] = 0;

    if(cnt > 1)
    {
        pq[1] = pq[cnt];
        pos[pq[1].second] = 1;
        --cnt;
        HeapDown(1);
    }
    else cnt--;

}

void inline bellman()
{
    for(short i = 1 ; i <= n ; i++)
        dist[i] = INT_MAX;

    dist[source] = 0;
    q.push(source);
    inq[source] = 1;

    while(!q.empty())
    {
        short node = q.front(); q.pop();
        inq[node] = 0;

        for(int j = 0 ; j < G[node].size() ; j++)
        {
            int i = G[node][j];

            if(capacity[node][i] && dist[node] + cost[node][i] < dist[i])
            {
                dist[i] = dist[node] + cost[node][i];
                if(!inq[i]) q.push(i);
                inq[i] = 1;
            }
        }
    }
}

bool inline djikstra()
{
    for(short i = 1 ; i <= n ; i++)
        d[i] = INT_MAX , parent[i] = 0;

    d[source] = 0;
    insert({0 , source});

    while(cnt)
    {
        short node = pq[1].second;
        int curr_dist = pq[1].first;
        pop();

        if(d[node] != curr_dist) continue;

        for(short j = 0 ; j < G[node].size() ; j++)
        {
            short to = G[node][j];

            if(capacity[node][to] && d[node] + (dist[node] + cost[node][to] - dist[to]) < d[to])
            {
                d[to] = d[node] + (dist[node] + cost[node][to] - dist[to]);
                parent[to] = node;
                insert({d[to] , to});
            }
        }
    }

    return d[sink] != INT_MAX;
}

int inline Flow()
{
    int flow = 0;
    int mnCost = 0;

    while(djikstra())
    {
        int mnFlow = INT_MAX;

        for(short curr = sink ; curr != source ; curr = parent[curr])
            mnFlow = min(mnFlow , (int) capacity[parent[curr]][curr]);

        flow += mnFlow;

        for(short curr = sink ; curr != source ; curr = parent[curr])
        {
            capacity[parent[curr]][curr] -= mnFlow;
            capacity[curr][parent[curr]] += mnFlow;
            mnCost += mnFlow * cost[parent[curr]][curr];
        }
    }

    return mnCost;
}

int main()
{
    ifstream f ("fmcm.in");
    ofstream g ("fmcm.out");

//    read(n) , read(m) , read(source) , read(sink);
    f >> n >> m >> source >> sink;

    while(m--)
    {
        f >> x >> y >> c >> z;
        //read(x) , read(y) , read(c) , read(z);

        G[x].pb(y);
        G[y].pb(x);

        capacity[x][y] = c;
        capacity[y][x] = 0;

        cost[x][y] = z;
        cost[y][x] = -z;
    }

    bellman();
    g << Flow();

    return 0;
}