#include <iostream>
#include <memory.h>
#include <string>
#include <istream>
#include <sstream>
#include <vector>
#include <stack>
#include <algorithm>
#include <map>
#include <queue>
#include <math.h>
#include <cstdio>
#include <set>
#include <iterator>
#include <cstring>
using namespace std;typedef long long LL;
const int MAXN = 5e4+10;
const int INF = 0x3f3f3f3f;struct Node
{int from_, to_, value_;Node(int from, int to, int value):from_(from), to_(to), value_(value){}bool operator < (const Node &that) const{return this->value_ > that.value_;}
};vector<Node> G[MAXN];
stack<int> St;
int Dfn[MAXN], Low[MAXN];
int Vis[MAXN], Dis[MAXN];
int Fa[MAXN], Val[MAXN];
int Num[MAXN];
int n, m;
int times, cnt;void Init()
{for (int i = 1;i <= n;i++)G[i].clear(), Fa[i] = i;memset(Dfn, 0, sizeof(Dfn));memset(Low, 0, sizeof(Low));memset(Vis, 0, sizeof(Vis));memset(Dis, 0, sizeof(Dis));memset(Num, 0, sizeof(Num));memset(Val, 0, sizeof(Val));times = cnt = 0;
}void Tarjan(int x)
{Dfn[x] = Low[x] = ++times;Vis[x] = 1;St.push(x);for (int i = 0;i < G[x].size();i++){int node = G[x][i].to_;if (Dfn[node] == 0){Tarjan(node);Low[x] = min(Low[x], Low[node]);}else if (Vis[node] == 1)Low[x] = min(Low[x], Dfn[node]);}if (Low[x] == Dfn[x]){cnt++;Num[cnt] = 0;while (St.top() != x){Num[cnt]++;Fa[St.top()] = cnt;Vis[St.top()] = 0;St.pop();}Num[cnt]++;Fa[St.top()] = cnt;Vis[St.top()] = 0;St.pop();}
}int main()
{int t, cn = 0;while (~scanf("%d%d", &n, &m)){Init();int l, r, v;for (int i = 1;i <= m;i++){scanf("%d%d%d", &l, &r, &v);l++, r++;G[l].emplace_back(l, r, v);}for (int i = 1;i <= n;++i)if (!Dfn[i])Tarjan(i);for (int i = 1;i <= cnt;i++)Val[i] = INF;for (int i = 1;i <= n;i++){for (int j = 0;j < G[i].size();j++){int node = G[i][j].to_;if (Fa[i] != Fa[node])Val[Fa[node]] = min(Val[Fa[node]], G[i][j].value_);}}int res = 0;for (int i = 1;i <= cnt;i++)if (Val[i] != INF)res += Val[i];cout << res << endl;}return 0;
}