#include<iostream>
#include<fstream>
#include<string.h>
#include<vector>
#include<queue>
#include<bitset>
#include<set>

using namespace std;

#define NMAX 355
#define INF 0X3f3f3f3f

int fluxMax[NMAX][NMAX], fluxSol[NMAX][NMAX], bmf[NMAX], T[NMAX], realC[NMAX];

void bellmanFord(int n, int S, vector< pair<int, int> > *adj){  //specificat in enunt ca nu sunt cicluri !!!
   	  
   	  int y, cost, q[n+3];
	  bitset<NMAX> inQueue(false);
   	  vector< pair<int,int> > :: iterator it;
   	  
   	  memset(bmf, INF, sizeof(bmf));
   	  q[0] = 1; q[1] = S; 
   	  inQueue[S]=true; bmf[S]=0;
   	  
   	  for( int i=1; i<=q[0]; i++){
   	  	 
   	  	 int x = q[i];
   	  	 inQueue[x] = false;
   	     
   	    for(it = adj[x].begin(); it != adj[x].end(); it++ ){
   	       
		   y = it->first; cost = it->second;
   	       if( !fluxMax[x][y] ) continue;
   	       if( bmf[y] > bmf[x] + cost ){
   	     	  bmf[y] = bmf[x] + cost;
   	     	  if( !inQueue[y] ){
   	     	   	   q[++q[0]] = y;
				   inQueue[y] = true;	
				  }
		   }
		}	
	  }
}


bool dijkstra( int n, int S, int D, vector< pair<int, int> > *adj ){
	
	int cAux[n+2], costUntil, x, y, cost;
	vector< pair<int, int> > :: iterator it;
	
	for(int i=1; i<=n; i++){
		T[i] = -1;
		cAux[i] = INF;
	}
	
	set< pair<int,int> > q;
	q.insert( make_pair(0,S) ); cAux[S] = 0;
	
	while(!q.empty()){
		
		x = q.begin()->second; 
		costUntil = q.begin()->first;
		q.erase(q.begin());
		
		if( x == D || cAux[x] != costUntil ) continue;
		
		for( it = adj[x].begin(); it != adj[x].end(); it++){
		
			y = it->first; cost = it->second;
			if( fluxMax[x][y] - fluxSol[x][y] <= 0 ) continue; 
			if( costUntil + cost + bmf[x] - bmf[y] < cAux[y] ){
			       cAux[y] = costUntil + cost + bmf[x] - bmf[y];
				   q.insert( make_pair(cAux[y],y) );	
				   T[y] = x; 
				   realC[y] = realC[x] + cost;
			}
		}
	}
	
	memcpy(bmf,realC,sizeof(realC)); 
	return !(cAux[D] == INF );
}


int main(){
	int nod, n, m, S, D, x, y, f, c, fMin, minC=0;
	FILE *in = fopen("fmcm.in","r");
	
	//citire
	fscanf(in,"%i %i %i %i", &n, &m, &S, &D);
	vector< pair<int,int> > adj[n+2]; // <destinatie arc, cost>
	
	while(m--){
		fscanf(in,"%i %i %i %i",&x, &y, &f, &c);
		adj[x].push_back( make_pair(y,c) );
		adj[y].push_back( make_pair(x,-c) );
		fluxMax[x][y] = f;
	}
	
	fclose(in);
	
	bellmanFord(n, S, adj);	
	
	while ( dijkstra(n, S, D, adj) ){
		
		fMin = INF;
		
		for(nod = D; nod != S; nod = T[nod])
		    fMin = min( fMin, fluxMax[ T[nod] ][ nod ] - fluxSol[ T[nod] ][ nod ]);
		    
		for(nod = D; nod != S; nod = T[nod]){
			fluxSol[ T[nod] ][ nod ] += fMin;
			fluxSol[ nod ][ T[nod] ] -= fMin;
		}
		
		minC += fMin * realC[D]; 
			
	}
	
	FILE *out = fopen("fmcm.out","w");
	fprintf(out,"%i",minC);
	fclose(out);
	return 0;
}