#include <cstdio>
#include <queue>

using namespace std;

struct Edge
{
  int to;
  int cap;
  int cost;
  int inv;
};

const int FN = 350 + 7;
const int FMAXDEG = FN;
const int INF = (int) 1e9 + 7;
int fln;
int fls;
int fld;
Edge fladj[FN][FMAXDEG];
int fltop[FN];
int fldist[FN];
bool flvis[FN];
int flparid[FN];
int flflow;
long long flflowcost;
queue<int> flq;

void flinit(int n, int s, int d)
{
  fln = n;
  fls = s;
  fld = d;
  flflow = 0;
  flflowcost = 0;
  for (int i = 1; i <= fln; i++)
  {
    fltop[i] = 0;
  }
}

void fladdedge(int a, int b, int cap, int cost)
{
  fltop[a]++;
  fltop[b]++;
  fladj[a][fltop[a]] = {b, cap, cost, fltop[b]};
  fladj[b][fltop[b]] = {a, 0, -cost, fltop[a]};
}

bool flbellman()
{
  for (int i = 1; i <= fln; i++)
  {
    fldist[i] = INF;
    flvis[i] = 0;
  }
  flq.push(fls);
  flvis[fls] = 1;
  fldist[fls] = 0;
  while (!flq.empty())
  {
    int a = flq.front();
    flvis[a] = 0;
    flq.pop();
    for (int j = 1; j <= fltop[a]; j++)
    {
      if (fladj[a][j].cap > 0 && fldist[a] + fladj[a][j].cost < fldist[fladj[a][j].to])
      {
        fldist[fladj[a][j].to] = fldist[a] + fladj[a][j].cost;
        flparid[fladj[a][j].to] = fladj[a][j].inv;
        if (!flvis[fladj[a][j].to])
        {
          flvis[fladj[a][j].to] = 1;
          flq.push(fladj[a][j].to);
        }
      }
    }
  }
  if (fldist[fld] == INF)
  {
    return 0;
  }
  int mn = INF, v = fld, s = 0;
  while (v != fls)
  {
    int cur = flparid[v];
    mn = min(mn, fladj[fladj[v][cur].to][fladj[v][cur].inv].cap);
    v = fladj[v][cur].to;
  }
  v = fld;
  while (v != fls)
  {
    int cur = flparid[v];
    fladj[fladj[v][cur].to][fladj[v][cur].inv].cap -= mn;
    fladj[v][cur].cap += mn;
    s += fladj[fladj[v][cur].to][fladj[v][cur].inv].cost;
    v = fladj[v][cur].to;
  }
  flflow += mn;
  flflowcost += 1LL * mn * fldist[fld];
  return 1;
}

void flpumpflow()
{
  while (flbellman())
  {

  }
}

signed main()
{
  freopen ("fmcm.in", "r", stdin);
  freopen ("fmcm.out", "w", stdout);

  int n, m, s, d;
  scanf("%d %d %d %d", &n, &m, &s, &d);
  flinit(n, s, d);
  for (int i = 1; i <= m; i++)
  {
    int a, b, c, d;
    scanf("%d %d %d %d", &a, &b, &c, &d);
    fladdedge(a, b, c, d);
  }
  flpumpflow();
  printf("%lld\n", flflowcost);

  return 0;
}
/**

**/