/*
很明显是最小费用最大流,中间所有的路径的流都是1,费用是路径长度
由于顶点太多,必须使用邻接表了
*/
// include file
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <cctype>
#include <ctime>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <bitset>
#include <strstream>
#include <algorithm>
#include <string>
#include <vector>
#include <queue>
#include <set>
#include <list>
#include <functional>
using namespace std;
// typedef
typedef long long LL;
typedef unsigned long long ULL;
//
#define read freopen("in.txt","r",stdin)
#define write freopen("out.txt","w",stdout)
#define FORi(a,b,c) for(int i=(a);i<(b);i+=c)
#define FORj(a,b,c) for(int j=(a);j<(b);j+=c)
#define FORk(a,b,c) for(int k=(a);k<(b);k+=c)
#define FORp(a,b,c) for(int p=(a);p<(b);p+=c)
#define FF(i,a) for(int i=0;i<(a);i+++)
#define FFD(i,a) for(int i=(a)-1;i>=0;i--)
#define Z(a) (a<<1)
#define Y(a) (a>>1)
const double eps = 1e-6;
const double INFf = 1e10;
const int INFi = 1000000000;
const double Pi = acos(-1.0);
template<class T> inline T sqr(T a){return a*a;}
template<class T> inline T TMAX(T x,T y)
{
if(x>y) return x;
return y;
}
template<class T> inline T TMIN(T x,T y)
{
if(x<y) return x;
return y;
}
template<class T> inline void SWAP(T &x,T &y)
{
T t = x;
x = y;
y = t;
}
template<class T> inline T MMAX(T x,T y,T z)
{
return TMAX(TMAX(x,y),z);
}
// code begin
#define MAXN 1010
#define MAXM 41000
struct node
{
int s;
int e;
int next;
int remain;
int cost;
};
node mem[MAXM];
int G[MAXN];
class MinCostMaxFlow_fordfulkerson_SPFA_queue
{
private:
int N,source,sink;
int dx;
// SPFA用
int dist[MAXN];
int isin[MAXN];
int cnt[MAXN];
int fat[MAXN];
int que[MAXN]; //BFS用
int flow;
int cost;
public:
MinCostMaxFlow_fordfulkerson_SPFA_queue(){}
void Set(int Nt,int sourcet,int sinkt)
{
N = Nt;
source = sourcet;
sink = sinkt;
}
void Init()
{
dx = 0;
memset(G,-1,sizeof(G));
}
void Add_edge(int a,int b,int f,int c)
{
mem[dx].s = a;
mem[dx].e = b;
mem[dx].remain = f;
mem[dx].cost = c;
mem[dx].next = G[a];
G[a] = dx++;
mem[dx].s = b;
mem[dx].e = a;
mem[dx].remain = 0;
mem[dx].cost = -c;
mem[dx].next = G[b];
G[b] = dx++;
}
int Getflow(){return flow;}
int Getcost(){return cost;}
public:
int SPFA() // bellman ford queue optimization
{
// from source
fill(dist,dist+N+1,INFi);
memset(isin,0,sizeof(isin));
memset(cnt,0,sizeof(cnt));
int head(0),tail(0);
dist[source] = 0;
que[tail] = source;
tail = (tail+1)%MAXN;
isin[source] = true;
cnt[source] ++;
while(head!=tail)
{
int cur = que[head];
isin[cur] = false;
head = (head+1)%MAXN;
int mdx = G[cur];
while(mdx!=-1)
{
int v = mem[mdx].e;
if( mem[mdx].remain!=0 && dist[cur]+mem[mdx].cost<dist[v])
{
dist[v] = dist[cur] + mem[mdx].cost;
fat[v] = mdx;
if(!isin[v])
{
isin[v] = true;
cnt[v] ++;
que[tail] = v;
tail = (tail+1)%MAXN;
}
}
mdx = mem[mdx].next;
}
}
if(dist[sink]==INFi) return -1;
return dist[sink];
}
int Augment()
{
int minp = INFi;
int mdx = fat[sink];
while(mem[mdx].s!=source)
{
if( mem[mdx].remain<minp )
{
minp = mem[mdx].remain;
}
mdx = fat[mem[mdx].s];
}
mdx = fat[sink];
while(mem[mdx].s!=source)
{
mem[mdx].remain -= minp;
mem[mdx^1].remain += minp;
mdx = fat[mem[mdx].s];
}
return minp;
}
void mincostmaxflow()
{
cost=0;
flow=0;
int fdx;
int cdx;
while((cdx=SPFA())!=-1)
{
fdx = Augment();
cost += cdx*fdx;
flow += fdx;
}
}
};
int N,M,source,sink;
MinCostMaxFlow_fordfulkerson_SPFA_queue g;
int main()
{
read;
write;
int a,b,c;
while(scanf("%d %d",&N,&M)!=-1)
{
source = N+1;
sink = N+2;
g.Init();
g.Set(N+2,source,sink);
FORi(1,M+1,1)
{
scanf("%d %d %d",&a,&b,&c);
g.Add_edge(a,b,1,c);
g.Add_edge(b,a,1,c);
}
g.Add_edge(source,1,2,0);
g.Add_edge(N,sink,2,0);
g.mincostmaxflow();
printf("%d\n",g.Getcost());
}
return 0;
}