#include <stdio.h>

#define Nmax 351
#define Inf 1000000000

int cost[Nmax][Nmax];
int flux[Nmax][Nmax];
int cap[Nmax][Nmax];
int n,m, Sursa, Destinatie;
int l[Nmax][Nmax];

int dist_min[Nmax];
int q[Nmax*Nmax];
int t[Nmax];
char viz[Nmax];

int rasp = 0;

int belman() {
  int i, st = 0, dr = 1;
  for (i = 1; i <= n; ++i) {
    dist_min[i] = Inf;
    viz[i] = 0;
  }
  
  q[1] = Sursa;
  dist_min[Sursa] = 0;
  viz[Sursa] = 1;

  while (st < dr) {
    int nod = q[++st];
    
    for (i = 1; i <= l[nod][0]; ++i)
    if ((cap[nod][l[nod][i]] - flux[nod][l[nod][i]] > 0) &&
       (dist_min[l[nod][i]] > dist_min[nod] + cost[nod][l[nod][i]])) {
      dist_min[l[nod][i]] = dist_min[nod] + cost[nod][l[nod][i]];
      t[l[nod][i]] = nod;
      if (viz[l[nod][i]] == 0) {
        viz[l[nod][i]] = 1;
        q[++dr] = l[nod][i];
      }
    }
    
    viz[nod] = 0;
  }

  return dist_min[Destinatie] < Inf;
}

void baga_fluxu() {
  int Min = cap[t[Destinatie]][Destinatie] - flux[t[Destinatie]][Destinatie];
  int nod;
  
  for (nod = t[Destinatie]; nod != Sursa; nod = t[nod])
  if (Min > cap[t[nod]][nod] - flux[t[nod]][nod])
    Min = cap[t[nod]][nod] - flux[t[nod]][nod];

  for (nod = Destinatie; nod != Sursa; nod = t[nod]) {
    flux[t[nod]][nod] += Min;
    flux[nod][t[nod]] -= Min;
  }
  
  rasp += Min*dist_min[Destinatie];
}



int main() {
  freopen("fmcm.in" , "r", stdin );
  freopen("fmcm.out", "w", stdout);
  
  scanf("%d%d%d%d", &n, &m, &Sursa, &Destinatie);
  
  int i, A, B;
  
  for (i = 1; i <= m; ++i) {
    scanf("%d%d", &A, &B);
    scanf("%d%d", &cap[A][B], &cost[A][B]);
    cost[B][A] = - cost[A][B];
    l[A][++l[A][0]] = B;
    l[B][++l[B][0]] = A;
  }

  while (belman())
    baga_fluxu();

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

  return 0;
}