#include <stdio.h>
#include <assert.h>
#include <stdlib.h>
#include <limits.h>
#include <unistd.h>

int N=INT_MAX,N1,N2,TOT=0;
char tty;

struct E {
	struct E *next,*forw;
	struct V *s,*d;
	int f,c;
	};

struct V {
	struct V *path;
	struct E *e,*back;
	} *V,**patht;

static void get(const char *s,int *vp)
{
int i;

	if (tty) { fputs(s,stdout); fputs(": ",stdout); fflush(stdout); }
	i=scanf("%d",vp); assert(i==1);
	assert(*vp>=1 && *vp<=N);
}

int main(void)
{
int i,V1,V2,C,diff;

	tty=!!ttyname(STDIN_FILENO);
	get("Number of cities",&N ); assert(N>=2);
	get("Starting city #" ,&N1);
	get("Ending   city #" ,&N2);
	if (tty) puts("Write <start city> <end city> <capacity> triples. Finish by EOF");
	V=calloc(N+1,sizeof(*V)); assert(V);
	while ((i=scanf("%d%d%d",&V1,&V2,&C))==3) {
struct E *e,*e0,*e1;

		assert(V1>=1 && V1<=N && V2>=1 && V2<=N && V1!=V2 && C>0);
		for (e=V[V1].e;e;e=e->next) assert(!(e->forw==e && e->d==V+V2));
		e0=malloc(sizeof(*e0)); assert(e0);
		e1=malloc(sizeof(*e1)); assert(e1);
		e0->next=V[V1].e; V[V1].e=e0;
		e1->next=V[V2].e; V[V2].e=e1;
		e0->s=V+V1; e0->d=V+V2;
		e1->s=V+V2; e1->d=V+V1;
		e0->forw=e1->forw=e0;
		e0->f=0; e0->c=C;
		e1->f=e1->c=-1;
		}
	assert(i<=0);

	for (;;) {
struct V *p,*p2;
struct E *e;
int d;

		for (i=1;i<=N;i++) V[i].path=NULL;
		patht=&V[N1].path;
		V[N1].back=NULL;
		for (p=V+N1;p && p!=V+N2;p=p->path)
			for (e=p->e;e;e=e->next)
				if (!e->d->path &&
					(( e==e->forw && e->f<e->c    )
				 ||( e!=e->forw && e->forw->f>0 ))) {
					*patht=e->d; patht=&e->d->path;
					e->d->back=e;
					}
		if (!p) break;
		diff=INT_MAX;
		for (p2=p;(e=p->back);p=e->s) {
			d=(e==e->forw ? e->c-e->f : e->f);
			assert(d>0);
			if (d<diff) diff=d;
			}
		assert(p==V+N1); assert(diff>0 || diff<INT_MAX);

		for (p=p2;(e=p->back);p=e->s)
			if (e==e->forw) e->f+=diff;
			else            e->f-=diff;
		if (p2->back->forw==p2->back) TOT+=diff;
		else                          TOT-=diff;
		assert(TOT>0);
		}
	printf("Total network flow is: %d\n",TOT);
	return(EXIT_SUCCESS);
}