//Author:xht37
#include <bits/stdc++.h>

#define ui unsigned int
#define ll long long
#define ul unsigned ll
#define ld long double

#define pi pair <int, int>
#define fi first
#define se second
#define mp make_pair

#define ls (p << 1)
#define rs (ls | 1)
#define md ((t[p].l + t[p].r) >> 1)

#define vi vector <int>
#define pb push_back
#define pq priority_queue

#define dbg(x) cerr << #x" = " << x << endl
#define debug(...) fprintf(stderr, __VA_ARGS__)

#define fl(x) freopen(x".in", "r", stdin), freopen(x".out", "w", stdout)

using namespace std;

namespace io {
	const int SI = 1 << 21 | 1;
	char IB[SI], *IS, *IT, OB[SI], *OS = OB, *OT = OS + SI - 1, c, ch[100];
	int f, t;
	#define gc() (IS == IT ? (IT = (IS = IB) + fread(IB, 1, SI, stdin), IS == IT ? EOF : *IS++) : *IS++)
	inline void flush() {
		fwrite(OB, 1, OS - OB, stdout), OS = OB;
	}
	inline void pc(char x) {
		*OS++ = x;
		if (OS == OT) flush();
	}

	template <class I>
	inline void rd(I &x) {
		for (f = 1, c = gc(); c < '0' || c > '9'; c = gc()) if (c == '-') f = -1;
		for (x = 0; c >= '0' && c <= '9'; x = (x << 3) + (x << 1) + (c & 15), c = gc());
		x *= f;
	}
	template <class I>
	inline void rd(I &x, I &y) {
		rd(x), rd(y);
	}
	template <class I>
	inline void rd(I &x, I &y, I &z) {
		rd(x), rd(y), rd(z);
	}
	template <class I>
	inline void rda(I *a, int n) {
		for (int i = 1; i <= n; i++) rd(a[i]);
	}
	inline void rdc(char &c) {
		for (c = gc(); c < 33 || c > 126; c = gc());
	}
	inline void rds(char *s, int &n) {
		for (c = gc(); c < 33 || c > 126; c = gc());
		for (n = 0; c >= 33 && c <= 126; s[++n] = c, c = gc());
		s[n+1] = '\0';
	}
	inline void rds(string &s) {
		for (c = gc(); c < 33 || c > 126; c = gc());
		for (s.clear(); c >= 33 && c <= 126; s.pb(c), c = gc());
	}

	template <class I>
	inline void print(I x, char k = '\n') {
		if (!x) pc('0');
		if (x < 0) pc('-'), x = -x;
		while (x) ch[++t] = x % 10 + '0', x /= 10;
		while (t) pc(ch[t--]);
		pc(k);
	}
	template <class I>
	inline void print(I x, I y) {
		print(x, ' '), print(y);
	}
	template <class I>
	inline void print(I x, I y, I z) {
		print(x, ' '), print(y, ' '), print(z);
	}
	template <class I>
	inline void printa(I *a, int n) {
		for (int i = 1; i <= n; i++) print(a[i], " \n"[i==n]);
	}
	inline void printc(char c) {
		pc(c);
	}
	inline void prints(char *s, int n) {
		for (int i = 1; i <= n; i++) pc(s[i]);
		pc('\n');
	}
	inline void prints(string s) {
		int n = s.length();
		while (t < n) pc(s[t++]);
		pc('\n'), t = 0;
	}
	struct Flush {
		~Flush() {
			flush();
		}
	} flusher;
}
using io::rd;
using io::rda;
using io::rdc;
using io::rds;
using io::print;
using io::printa;
using io::printc;
using io::prints;

const int N = 1e5 + 7;
int n, m, a[N], b[N], c[N], d[N], f[N], s[N];
bool v[N];
vi p1, p2, p3, p4;
ll ans, cnt, sum, now;

int get(int x) {
	return x == f[x] ? x : (f[x] = get(f[x]));
}

int main() {
//	fl("1");
	rd(n, m);
	for (int i = 1; i <= n; i++) f[i] = i, v[i] = 1;
	for (int i = 1; i <= m; i++)
		rd(a[i], b[i], c[i]), ++d[a[i]],
		f[get(a[i])] = get(b[i]), ans += a[i] != b[i];
	for (int i = 1; i <= n; i++) {
		++s[get(i)];
		if (d[i] != 1) v[get(i)] = 0;
	}
	for (int i = 1; i <= n; i++)
		cnt += get(i) == i && v[i] && s[i] > 1;
	if (!cnt) return print(ans), 0;
	ans += cnt;
	for (int i = 1; i <= m; i++) {
		if (c[i] == 1) continue;
		int x = get(i);
		if (v[x] && s[x] == 1) p1.pb(c[i] - 2);
		if (v[x] && s[x] > 1) p2.pb(c[i] - 1);
		if (!v[x] && a[i] == b[i]) p3.pb(c[i] - 1);
		if (!v[x] && a[i] != b[i]) p4.pb(c[i] - 1);
	}
	for (int x : p1) sum += x;
	for (int x : p2) sum += x;
	for (int x : p3) sum += x;
	for (int x : p4) sum += x;
//	dbg(sum), dbg(cnt), dbg(p3.size()), dbg(p4.size());
	if (sum < cnt || (p3.empty() && p4.empty())) return print(-1), 0;
	sort(p1.begin(), p1.end());
	sort(p2.begin(), p2.end());
	sort(p3.begin(), p3.end());
	sort(p4.begin(), p4.end());
	if (p4.size()) cnt -= p4.back(), p4.pop_back();
	else ++ans, cnt -= p3.back(), p3.pop_back();
	for (int x : p2) cnt -= x;
	for (int x : p4) cnt -= x;
	if (cnt <= 0) return print(ans), 0;
	now = ans, ans = 1e18, sum = 0;
	for (int x : p3) sum += x;
	for (int i = p1.size(), j = 0; ~i; i--) {
		if (i < (int)p1.size()) sum += p1[i];
		while (j < (int)p3.size() && sum - p3[j] >= cnt) sum -= p3[j++];
		if (sum >= cnt) ans = min(ans, now + 2 * ((int)p1.size() - i) + ((int)p3.size() - j));
	}
//	dbg(ans);
	print(ans);
	return 0;
}

Measured memory_bytes: 7984