#include<algorithm>
#include<bitset>
#include<cmath>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<ctime>
#include<deque>
#include<fstream>
#include<iomanip>
#include<iostream>
#include<map>
#include<queue>
#include<set>
#include<stack>
#include<unordered_map>
#include<unordered_set>
#include<utility>
#include<vector>

using namespace std;

#ifdef HOME
const string inputFile = "input.txt";
const string outputFile = "output.txt";
#else
const string problemName = "fmcm";
const string inputFile = problemName + ".in";
const string outputFile = problemName + ".out";
#endif

const int NMAX = 350 + 5;
const int INF = (1 << 30);

int N, M;
vector<int> V[NMAX];
int C[NMAX][NMAX];
int F[NMAX][NMAX];
int D[NMAX][NMAX];
int dist[NMAX];
bitset<NMAX> viz;
deque<int> Q;
int dad[NMAX];
int source, sink, maxflow, mincost;

int bf() {
    int i, x;

    viz = 0;
    Q.clear();

    for(i = 1; i <= N; i++)
        dist[i] = INF;

    dist[source] = 0;
    viz[source] = 1;
    Q.push_back(source);

    while(!Q.empty()) {
        x = Q.front();
        Q.pop_front();
        viz[x] = 0;

        for(auto y : V[x])
            if((F[x][y] < C[x][y]) && (dist[x] + D[x][y] < dist[y])) {
                dist[y] = dist[x] + D[x][y];
                dad[y] = x;
                if(!viz[y]) {
                    viz[y] = 1;
                    Q.push_back(y);
                }
            }
    }

    return (dist[sink] != INF);
}

int main() {
    int x, y, z, c, v;

#ifndef ONLINE_JUDGE
    freopen(inputFile.c_str(), "r", stdin);
    freopen(outputFile.c_str(), "w", stdout);
#endif

    scanf("%d%d%d%d", &N, &M, &source, &sink);

    while(M--) {
        scanf("%d%d%d%d", &x, &y, &z, &c);

        V[x].push_back(y);
        V[y].push_back(x);

        C[x][y] = z;

        D[x][y] = c;
        D[y][x] = -c;
    }

    while(bf()) {
        v = INF;

        for(x = sink; x != source; x = dad[x])
            v = min(v, C[dad[x]][x] - F[dad[x]][x]);

        for(x = sink; x != source; x = dad[x]) {
            F[dad[x]][x] += v;
            F[x][dad[x]] -= v;
        }

        maxflow += v;
        mincost += v * dist[sink];
    }

    printf("%d\n", mincost);

    return 0;
}