#include <iostream>
#include <string.h>
#include <random>
#include <fstream>
#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <iomanip>
#include <algorithm>
#include <math.h>
#include <cmath>
#include <vector>
#include <stack>
#include <queue>
#include <bitset>
#include <map>
#include <set>
#include <unordered_map>
#include <unordered_set>
#include <complex>
//#include <ext/pb_ds/assoc_container.hpp>
//using namespace __gnu_pbds;
using namespace std;
typedef pair<int, int> pii;
typedef pair<int, string> pis;
typedef pair<string, string> pss;
typedef pair<int, char> pic;
typedef pair<pii, int> piii;
typedef pair<double, double> pdd;
typedef long long ll;
typedef unsigned long long ull;
typedef unsigned int uint;
typedef pair<ll, ll> pll;
typedef pair<int, ll> pil;
typedef pair<ull, ull> pull;
typedef complex<double> cd;
//#define max(n, m) ((n>m)?n:m)
//#define min(n, m) ((n<m)?n:m)
#define f first
#define s second
#define input() ios_base::sync_with_stdio(0);cin.tie(0);

ifstream fin("fmcm.in");
ofstream fout("fmcm.out");
 
vector<int> adj[360];
priority_queue<piii, vector<piii>, greater<piii>> nextInLine;
bitset<360> visited;
ll cur[360][360], lim[360][360], cost[360][360], par[360], dist[360];
int main()
{
    input();
    ll n, m, st, en, a, b, c, d, curN, curD, curP, curF, flow = 0, ans = 0;
    fin >> n >> m >> st >> en; st--; en--;
    for(int i = 0; i < m; i ++)
    {
        fin >> a >> b >> c >> d; a--; b--;
        adj[a].push_back(b); adj[b].push_back(a);
        lim[a][b] += c; cost[a][b] += d; cost[b][a] -= d;
    }
    for(int i = 0; i < n; i ++)
        dist[i] = 2000000000;
    dist[st] = 0;
    for(int cnt = 0; cnt < n; cnt ++)
        for(int i = 0; i < n; i ++)
            for(auto it : adj[i])
                if(lim[i][it])
                    if(dist[i] + cost[i][it] < dist[it])
                        dist[it] = dist[i] + cost[i][it];
    for(int i = 0; i < n; i ++)
        for(auto it : adj[i])
        {
            cost[i][it] += (dist[i] - dist[it]);
            cout << "";
            continue;
        }
    while(true)
    {
        nextInLine.push({{0, -1}, st});
        visited.reset();
        while(!nextInLine.empty())
        {
            curD = nextInLine.top().f.f; curP = nextInLine.top().f.s; curN = nextInLine.top().s;
            nextInLine.pop();
            if(!visited[curN])
            {
                visited[curN] = true;
                par[curN] = curP;
                if(curN == en)
                {
                    d = curD;
                    continue;
                }
                for(auto it : adj[curN])
                    if(cur[curN][it] != lim[curN][it])
                    {
                        nextInLine.push({{curD + cost[curN][it], curN}, it});
                    }
            }
        }
        if(!visited[en]) break;
        curF = 2000000000; curN = en;
        while(curN != st)
        {
            curF = min(curF, lim[par[curN]][curN] - cur[par[curN]][curN]);
            curN = par[curN];
        }
        curN = en;
        while(curN != st)
        {
            cur[par[curN]][curN] += curF;
            cur[curN][par[curN]] -= curF;
            curN = par[curN];
        }
        flow += curF * (d + dist[en]);
    }
    fout << flow << "\n";
}