#include<bits/stdc++.h>
using namespace std;
#define int long long
#define pb push_back
#define ld double
#define ll __int128
mt19937 rnd(51);
const int INF = 1e14 + 100;
struct st {
vector<int> t, add, arr;
void build(int v, int l, int r) {
if (l == r) {
t[v] = arr[l];
return;
}
int m = (l + r) / 2;
build(2 * v, l, m), build(2 * v + 1, m + 1, r);
}
st(vector<int> a) {
int n = a.size();
arr = a;
t.resize(4 * n);
add.resize(4 * n);
build(1, 0, n - 1);
}
void push(int v) {
t[v] += add[v];
if (v * 2 < add.size()) {
add[v * 2] += add[v];
add[v * 2 + 1] += add[v];
}
add[v] = 0;
}
void update(int v, int tl, int tr, int l, int r, int val) {
if (l > r) return;
if (tl == l && tr == r) {
add[v] += val;
return;
}
int tm = (tl + tr) / 2;
update(2 * v, tl, tm, l, min(r, tm), val), update(2 * v + 1, tm + 1, tr, max(l, tm + 1), r, val);
}
int get(int v, int l, int r, int pos) {
push(v);
if (l == r) {
return t[v];
}
int m = (l + r) / 2;
if (pos <= m) {
return get(2 * v, l, m, pos);
} else {
return get(2 * v + 1, m + 1, r, pos);
}
}
};
signed main() {
#ifdef LOCAL
freopen("input.txt", "r", stdin);
#endif // LOCAL
ios_base::sync_with_stdio(0);
cin.tie(0);
int n, q;
cin >> n >> q;
vector<int> a(q), b(q), c(q), pr(n + 1), d(n);
vector<vector<pair<int,int>>> need(n);
for (int i = 0; i < q; i++) {
cin >> a[i] >> b[i] >> c[i];
a[i]--, b[i]--;
if (a[i] > b[i]) swap(a[i], b[i]);
b[i]--;
pr[a[i]] += c[i], pr[b[i] + 1] -= c[i];
need[a[i]].pb({b[i], c[i]});
}
int sum = 0;
for (int i = 0; i < n; i++) {
sum += pr[i];
d[i] = sum;
}
int l = 0, r = INF;
int val = *max_element(d.begin(), d.end());
while (r - l > 1) {
int mid = (r + l) / 2;
bool ok = 0, bad = 0;
if (val <= mid) {
r = mid;
continue;
}
for (int m = val - mid; m <= val - mid + 1; m++) {
for (int j = 0; j < n; j++) {
d[j] += m;
}
st t(d);
for (int j = 0; j < n; j++) {
d[j] -= m;
}
multiset<pair<int,int>> st;
int cnt = 0;
for (int i = 0; i < n; i++) {
for (auto to : need[i]) {
st.insert(to);
}
int val = t.get(1, 0, n - 1, i);
while (val > mid) {
if (st.size() == 0) {
bad = 1;
break;
}
auto to = *st.rbegin();
st.erase(st.find(to));
if (2 * to.second >= val - mid) {
int need = (val - mid + 1) / 2;
t.update(1, 0, n - 1, i, to.first, -2 * need);
to.second -= need;
if (to.second > 0) {
st.insert(to);
}
cnt += need;
break;
} else {
t.update(1, 0, n - 1, i, to.first, -2 * to.second);
cnt += to.second;
val -= 2 * to.second;
}
}
if (bad) {
break;
}
}
if (cnt <= m && !bad) {
ok = 1;
break;
}
}
if (ok) {
r = mid;
} else {
l = mid;
}
}
cout << r << endl;
return 0;
}
