#ifdef LOCAL
#define _GLIBCXX_DEBUG
#endif
 
#include <bits/stdc++.h>
using namespace std;
#if __has_include(<atcoder/all>)
#include <atcoder/all>
using namespace atcoder;
#endif
 
#pragma region Macros
// rep macro
#define foa(v, a) for(auto &v : a)
#define REPname(a, b, c, d, e, ...) e
#define REP(...) REPname(__VA_ARGS__, REP3, REP2, REP1, REP0)(__VA_ARGS__)
#define REP0(x) for(int i = 0; i < (x); ++i)
#define REP1(i, x) for(int i = 0; i < (x); ++i)
#define REP2(i, l, r) for(int i = (l); i < (r); ++i)
#define REP3(i, l, r, c) for(int i = (l); i < (r); i += (c))
#define REPSname(a, b, c, ...) c
#define REPS(...) REPSname(__VA_ARGS__, REPS1, REPS0)(__VA_ARGS__)
#define REPS0(x) for(int i = 1; i <= (x); ++i)
#define REPS1(i, x) for(int i = 1; i <= (x); ++i)
#define RREPname(a, b, c, d, e, ...) e
#define RREP(...) RREPname(__VA_ARGS__, RREP3, RREP2, RREP1, RREP0)(__VA_ARGS__)
#define RREP0(x) for(int i = (x)-1; i >= 0; --i)
#define RREP1(i, x) for(int i = (x)-1; i >= 0; --i)
#define RREP2(i, l, r) for(int i = (r)-1; i >= (l); --i)
#define RREP3(i, l, r, c) for(int i = (r)-1; i >= (l); i -= (c))
#define RREPSname(a, b, c, ...) c
#define RREPS(...) RREPSname(__VA_ARGS__, RREPS1, RREPS0)(__VA_ARGS__)
#define RREPS0(x) for(int i = (x); i >= 1; --i)
#define RREPS1(i, x) for(int i = (x); i >= 1; --i)
 
// name macro
#define fi first
#define se second
#define pb push_back
#define eb emplace_back
#define SZ(x) ((int)(x).size())
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define popcnt(x) __builtin_popcountll(x)
template <class T = int>
using V = std::vector<T>;
template <class T = int>
using VV = std::vector<std::vector<T>>;
template <class T = int>
using VVV = std::vector<std::vector<std::vector<T>>>;
template <class T>
using pqup = std::priority_queue<T, std::vector<T>, std::greater<T>>;
using ll = long long;
using ld = long double;
using int128 = __int128_t;
using pii = std::pair<int, int>;
using pll = std::pair<long long, long long>;
using Tp = tuple<ll,ll,ll>;
 
// input macro
template <class T, class U>
std::istream &operator>>(std::istream &is, std::pair<T, U> &p) {
	is >> p.first >> p.second;
	return is;
}
template <class T>
std::istream &operator>>(std::istream &is, std::vector<T> &v) {
	for(T &i : v) is >> i;
	return is;
}
std::istream &operator>>(std::istream &is, __int128_t &a) {
	std::string s;
	is >> s;
	__int128_t ret = 0;
	for(int i = 0; i < s.length(); i++)
		if('0' <= s[i] and s[i] <= '9')
			ret = 10 * ret + s[i] - '0';
	a = ret * (s[0] == '-' ? -1 : 1);
	return is;
}
namespace scanner {
void scan(int &a) { std::cin >> a; }
void scan(long long &a) { std::cin >> a; }
void scan(std::string &a) { std::cin >> a; }
void scan(char &a) { std::cin >> a; }
void scan(char a[]) { std::scanf("%s", a); }
void scan(double &a) { std::cin >> a; }
void scan(long double &a) { std::cin >> a; }
template <class T, class U>
void scan(std::pair<T, U> &p) { std::cin >> p; }
template <class T>
void scan(std::vector<T> &a) { std::cin >> a; }
void INPUT() {}
template <class Head, class... Tail>
void INPUT(Head &head, Tail &... tail) {
	scan(head);
	INPUT(tail...);
}
}  // namespace scanner
#define VEC(type, name, size)     \
	std::vector<type> name(size); \
	scanner::INPUT(name)
#define VVEC(type, name, h, w)                                    \
	std::vector<std::vector<type>> name(h, std::vector<type>(w)); \
	scanner::INPUT(name)
#define INT(...)     \
	int __VA_ARGS__; \
	scanner::INPUT(__VA_ARGS__)
#define LL(...)            \
	long long __VA_ARGS__; \
	scanner::INPUT(__VA_ARGS__)
#define STR(...)             \
	std::string __VA_ARGS__; \
	scanner::INPUT(__VA_ARGS__)
#define CHAR(...)     \
	char __VA_ARGS__; \
	scanner::INPUT(__VA_ARGS__)
#define DOUBLE(...)     \
	double __VA_ARGS__; \
	scanner::INPUT(__VA_ARGS__)
#define LD(...)              \
	long double __VA_ARGS__; \
	scanner::INPUT(__VA_ARGS__)
 
// output-macro
template <class T, class U>
std::ostream &operator<<(std::ostream &os, const std::pair<T, U> &p) {
	os << p.first << " " << p.second;
	return os;
}
template <class T>
std::ostream &operator<<(std::ostream &os, const std::vector<T> &a) {
	for(int i = 0; i < int(a.size()); ++i) {
		if(i) os << " ";
		os << a[i];
	}
	return os;
}
std::ostream &operator<<(std::ostream &dest, __int128_t &value) {
	std::ostream::sentry s(dest);
	if(s) {
		__uint128_t tmp = value < 0 ? -value : value;
		char buffer[128];
		char *d = std::end(buffer);
		do {
			--d;
			*d = "0123456789"[tmp % 10];
			tmp /= 10;
		} while(tmp != 0);
		if(value < 0) {
			--d;
			*d = '-';
		}
		int len = std::end(buffer) - d;
		if(dest.rdbuf()->sputn(d, len) != len) {
			dest.setstate(std::ios_base::badbit);
		}
	}
	return dest;
}
template <class T>
void print(const T a) { std::cout << a << '\n'; }
template <class Head, class... Tail>
void print(Head H, Tail... T) {
	std::cout << H << ' ';
	print(T...);
}
template <class T>
void printel(const T a) { std::cout << a << '\n'; }
template <class T>
void printel(const std::vector<T> &a) {
	for(const auto &v : a)
		std::cout << v << '\n';
}
template <class Head, class... Tail>
void printel(Head H, Tail... T) {
	std::cout << H << '\n';
	printel(T...);
}
void Yes(const bool b = true) { std::cout << (b ? "Yes\n" : "No\n"); }
void No() { std::cout << "No\n"; }
void YES(const bool b = true) { std::cout << (b ? "YES\n" : "NO\n"); }
void NO() { std::cout << "No\n"; }
void err(const bool b = true) {
	if(b) {
		std::cout << "-1\n", exit(0);
	}
}
 
//debug macro
namespace debugger {
template <class T>
void view(const std::vector<T> &a) {
	std::cerr << "{ ";
	for(const auto &v : a) {
		std::cerr << v << ", ";
	}
	std::cerr << "\b\b }";
}
template <class T>
void view(const std::vector<std::vector<T>> &a) {
	std::cerr << "{\n";
	for(const auto &v : a) {
		std::cerr << "\t";
		view(v);
		std::cerr << "\n";
	}
	std::cerr << "}";
}
template <class T, class U>
void view(const std::vector<std::pair<T, U>> &a) {
	std::cerr << "{\n";
	for(const auto &p : a) std::cerr << "\t(" << p.first << ", " << p.second << ")\n";
	std::cerr << "}";
}
template <class T, class U>
void view(const std::map<T, U> &m) {
	std::cerr << "{\n";
	for(const auto &p : m) std::cerr << "\t[" << p.first << "] : " << p.second << "\n";
	std::cerr << "}";
}
template <class T, class U>
void view(const std::pair<T, U> &p) { std::cerr << "(" << p.first << ", " << p.second << ")"; }
template <class T>
void view(const std::set<T> &s) {
	std::cerr << "{ ";
	for(auto &v : s) {
		view(v);
		std::cerr << ", ";
	}
	std::cerr << "\b\b }";
}
 
template <class T>
void view(const T &e) { std::cerr << e; }
}  // namespace debugger
#ifdef LOCAL
void debug_out() {}
template <typename Head, typename... Tail>
void debug_out(Head H, Tail... T) {
	debugger::view(H);
	std::cerr << ", ";
	debug_out(T...);
}
#define debug(...)                                                \
	do {                                                          \
		std::cerr << __LINE__ << " [" << #__VA_ARGS__ << "] : ["; \
		debug_out(__VA_ARGS__);                                   \
		std::cerr << "\b\b]\n";                                   \
	} while(false)
#else
#define debug(...) (void(0))
#endif
 
// vector macro
template <class T>
int lb(const std::vector<T> &a, const T x) { return std::distance((a).begin(), std::lower_bound((a).begin(), (a).end(), (x))); }
template <class T>
int ub(const std::vector<T> &a, const T x) { return std::distance((a).begin(), std::upper_bound((a).begin(), (a).end(), (x))); }
template <class T>
void UNIQUE(std::vector<T> &a) {
	std::sort(a.begin(), a.end());
	a.erase(std::unique(a.begin(), a.end()), a.end());
}
template <class T>
std::vector<T> press(std::vector<T> &a) {
	auto res = a;
	UNIQUE(res);
	for(auto &v : a)
		v = lb(res, v);
	return res;
}
#define SORTname(a, b, c, ...) c
#define SORT(...) SORTname(__VA_ARGS__, SORT1, SORT0, ...)(__VA_ARGS__)
#define SORT0(a) std::sort((a).begin(), (a).end())
#define SORT1(a, c) std::sort((a).begin(), (a).end(), [](const auto x, const auto y) { return x c y; })
template <class T>
void ADD(std::vector<T> &a, const T x) {
	for(auto &v : a) v += x;
}
template <class T>
void SUB(std::vector<T> &a, const T x = 1) {
	for(auto &v : a) v -= x;
}
template <class T>
void MUL(std::vector<T> &a, const T x) {
	for(auto &v : a) v *= x;
}
template <class T>
void DIV(std::vector<T> &a, const T x) {
	for(auto &v : a) v /= x;
}
 
// math macro
template <class T, class U>
inline bool chmin(T &a, const U &b) { return a > b ? a = b, true : false; }
template <class T, class U>
inline bool chmax(T &a, const U &b) { return a < b ? a = b, true : false; }
template <class T>
T divup(T x, T y) { return (x + y - 1) / y; }
template <class T>
T POW(T a, long long n) {
	T ret = 1;
	while(n) {
		if(n & 1) ret *= a;
		a *= a;
		n >>= 1;
	}
	return ret;
}

template<typename T>
T ADD(T a, T b){
	T res;
	return __builtin_add_overflow(a, b, &res) ? numeric_limits<T>::max() : res;
}

template<typename T>
T MUL(T a, T b){
	T res;
	return __builtin_mul_overflow(a, b, &res) ? numeric_limits<T>::max() : res;
}

// modpow
long long POW(long long a, long long n, const int mod) {
	long long ret = 1;
	while(n) {
		if(n & 1) (ret *= a) %= mod;
		(a *= a) %= mod;
		n >>= 1;
	}
	return ret;
}
 
// others
struct fast_io {
	fast_io() {
		ios::sync_with_stdio(false);
		cin.tie(nullptr);
		cout << fixed << setprecision(15);
	}
} fast_io_;

#pragma endregion

using R = long double;
constexpr R EPS=1E-11;

// r の(誤差付きの)符号に従って, -1, 0, 1 を返す.
int sgn(const R& r){ return (r > EPS) - (r < -EPS); }
// a, b の(誤差付きの)大小比較の結果に従って, -1, 0, 1 を返す.
int sgn(const R& a, const R &b){ return sgn(a-b); }
// a > 0 は sgn(a) > 0
// a < b は sgn(a, b) < 0
// a >= b は sgn(a, b) >= 0
// のように書く.
// return s * 10^n

//https://atcoder.jp/contests/abc191/submissions/20028529
long long x10(const string& s, size_t n) {
    if (s.front() == '-') return -x10(s.substr(1), n);
    auto pos = s.find('.');
    if (pos == string::npos) return stoll(s + string(n, '0'));
    return stoll(s.substr(0, pos) + s.substr(pos + 1) + string(n + pos + 1 - s.size(), '0'));
}
 
long long ceildiv(long long a, long long b) {
    if (b < 0) a = -a, b = -b;
    if (a >= 0) return (a + b - 1) / b;
    else return a / b;
}
 
long long floordiv(long long a, long long b) {
    if (b < 0) a = -a, b = -b;
    if (a >= 0) return a / b;
    else return (a - b + 1) / b;
}
 
long long floorsqrt(long long x) {
    assert(x >= 0);
    long long ok = 0;
    long long ng = 1;
    while (ng * ng <= x) ng <<= 1;
    while (ng - ok > 1) {
        long long mid = (ng + ok) >> 1;
        if (mid * mid <= x) ok = mid;
        else ng = mid;
    }
    return ok;
}

inline int topbit(unsigned long long x){
	return x?63-__builtin_clzll(x):-1;
}

inline int popcount(unsigned long long x){
	return __builtin_popcountll(x);
}

inline int parity(unsigned long long x){//popcount%2
	return __builtin_parity(x);
}

const int inf = 1e9;
const ll INF = 1e18;

template <class T>
struct SegmentTreeBeats {
private:
	size_t n, n_;
	const T MAX = std::numeric_limits<T>::max();
	const T MIN = -MAX;
	std::vector<T> max_v, min_v, smax_v, smin_v, lz_upd, lz_ad, sigm, len;
	std::vector<int> max_c, min_c;
 
	void init(std::vector<T> &v) {
		n_ = v.size(), n = 1;
		while(n < n_) n *= 2;
		max_v.assign(n * 2 - 1, MIN);
		min_v.assign(n * 2 - 1, MAX);
		smax_v.assign(n * 2 - 1, MIN);
		smin_v.assign(n * 2 - 1, MAX);
		lz_upd.assign(n * 2 - 1, MAX);
		lz_ad.assign(n * 2 - 1, 0);
		len.assign(n * 2 - 1, n);
		sigm.assign(n * 2 - 1, 0);
		max_c.assign(n * 2 - 1, 1);
		min_c.assign(n * 2 - 1, 1);
 
		for(int i = 0; i < n - 1; i++)
			len[i * 2 + 1] = len[i * 2 + 2] = (len[i] >> 1);
 
		for(int i = 0; i < n_; i++)
			max_v[i + n - 1] = min_v[i + n - 1] = sigm[i + n - 1] = v[i];
 
		for(int i = n - 2; i >= 0; i--)
			proc(i);
	}
 
	void proc(int i) {
		sigm[i] = sigm[i * 2 + 1] + sigm[i * 2 + 2];
 
		max_v[i] = std::max(max_v[i * 2 + 1], max_v[i * 2 + 2]);
 
		if(max_v[i * 2 + 1] > max_v[i * 2 + 2]) {
			max_c[i] = max_c[i * 2 + 1];
			smax_v[i] = std::max(smax_v[i * 2 + 1], max_v[i * 2 + 2]);
		}
 
		if(max_v[i * 2 + 1] < max_v[i * 2 + 2]) {
			max_c[i] = max_c[i * 2 + 2];
			smax_v[i] = std::max(max_v[i * 2 + 1], smax_v[i * 2 + 2]);
		}
 
		if(max_v[i * 2 + 1] == max_v[i * 2 + 2]) {
			max_c[i] = max_c[i * 2 + 1] + max_c[i * 2 + 2];
			smax_v[i] = std::max(smax_v[i * 2 + 1], smax_v[i * 2 + 2]);
		}
 
		min_v[i] = std::min(min_v[i * 2 + 1], min_v[i * 2 + 2]);
 
		if(min_v[i * 2 + 1] < min_v[i * 2 + 2]) {
			min_c[i] = min_c[i * 2 + 1];
			smin_v[i] = std::min(smin_v[i * 2 + 1], min_v[i * 2 + 2]);
		}
 
		if(min_v[i * 2 + 1] > min_v[i * 2 + 2]) {
			min_c[i] = min_c[i * 2 + 2];
			smin_v[i] = std::min(min_v[i * 2 + 1], smin_v[i * 2 + 2]);
		}
 
		if(min_v[i * 2 + 1] == min_v[i * 2 + 2]) {
			min_c[i] = min_c[i * 2 + 1] + min_c[i * 2 + 2];
			smin_v[i] = std::min(smin_v[i * 2 + 1], smin_v[i * 2 + 2]);
		}
	}
 
	void eval(int i) {
		if(lz_upd[i] != MAX) {
			in_update(i * 2 + 1, lz_upd[i]);
			in_update(i * 2 + 2, lz_upd[i]);
			lz_upd[i] = MAX;
			return;
		}
 
		if(lz_ad[i]) {
			in_add(i * 2 + 1, lz_ad[i]);
			in_add(i * 2 + 2, lz_ad[i]);
			lz_ad[i] = 0;
		}
 
		if(max_v[i] < max_v[i * 2 + 1]) in_chmin(i * 2 + 1, max_v[i]);
		if(max_v[i] < max_v[i * 2 + 2]) in_chmin(i * 2 + 2, max_v[i]);
 
		if(min_v[i] > min_v[i * 2 + 1]) in_chmax(i * 2 + 1, min_v[i]);
		if(min_v[i] > min_v[i * 2 + 2]) in_chmax(i * 2 + 2, min_v[i]);
	}
 
	void in_update(int i, T x) {
		max_v[i] = min_v[i] = x;
		smax_v[i] = MIN, smin_v[i] = MAX;
		max_c[i] = min_c[i] = len[i];
		sigm[i] = len[i] * x;
		lz_upd[i] = x, lz_ad[i] = 0;
	}
 
	void in_chmin(int i, T x) {
		sigm[i] += (x - max_v[i]) * max_c[i];
 
		if(max_v[i] == min_v[i])
			max_v[i] = min_v[i] = x;
 
		else if(max_v[i] == smin_v[i])
			max_v[i] = smin_v[i] = x;
 
		else
			max_v[i] = x;
 
		if(lz_upd[i] != MAX and lz_upd[i] > x) lz_upd[i] = x;
	}
 
	void in_chmax(int i, T x) {
		sigm[i] += (x - min_v[i]) * min_c[i];
 
		if(min_v[i] == max_v[i])
			min_v[i] = max_v[i] = x;
 
		else if(min_v[i] == smax_v[i])
			min_v[i] = smax_v[i] = x;
 
		else
			min_v[i] = x;
 
		if(lz_upd[i] != MAX and lz_upd[i] < x) lz_upd[i] = x;
	}
 
	void in_add(int i, T x) {
		max_v[i] += x, min_v[i] += x;
 
		if(smin_v[i] != MAX) smin_v[i] += x;
		if(smax_v[i] != MIN) smax_v[i] += x;
 
		sigm[i] += x * len[i];
 
		if(lz_upd[i] != MAX) lz_upd[i] += x;
		lz_ad[i] += x;
	}
 
	void chmin(int i, int a, int b, int l, int r, T x) {
		if(b <= l or r <= a or x >= max_v[i]) return;
 
		if(a <= l and r <= b and smax_v[i] < x) {
			in_chmin(i, x);
			return;
		}
 
		eval(i);
		chmin(i * 2 + 1, a, b, l, (l + r) >> 1, x);
		chmin(i * 2 + 2, a, b, (l + r) >> 1, r, x);
		proc(i);
	}
 
	void chmax(int i, int a, int b, int l, int r, T x) {
		if(b <= l or r <= a or x <= min_v[i]) return;
 
		if(a <= l and r <= b and smin_v[i] > x) {
			in_chmax(i, x);
			return;
		}
 
		eval(i);
		chmax(i * 2 + 1, a, b, l, (l + r) >> 1, x);
		chmax(i * 2 + 2, a, b, (l + r) >> 1, r, x);
		proc(i);
	}
 
	void add(int i, int a, int b, int l, int r, T x) {
		if(b <= l or r <= a) return;
 
		if(a <= l and r <= b) {
			in_add(i, x);
			return;
		}
 
		eval(i);
		add(i * 2 + 1, a, b, l, (l + r) >> 1, x);
		add(i * 2 + 2, a, b, (l + r) >> 1, r, x);
		proc(i);
	}
 
	void update(int i, int a, int b, int l, int r, T x) {
		if(b <= l or r <= a) return;
 
		if(a <= l and r <= b) {
			in_update(i, x);
			return;
		}
 
		eval(i);
		update(i * 2 + 1, a, b, l, (l + r) >> 1, x);
		update(i * 2 + 2, a, b, (l + r) >> 1, r, x);
		proc(i);
	}
 
	T sum(int i, int a, int b, int l, int r) {
		if(r <= a || b <= l) return 0;
 
		if(a <= l && r <= b) return sigm[i];
 
		eval(i);
		T lv = sum(i * 2 + 1, a, b, l, (l + r) / 2);
		T rv = sum(i * 2 + 2, a, b, (l + r) / 2, r);
		return lv + rv;
	}
 
	T rangemin(int i, int a, int b, int l, int r) {
		if(r <= a or b <= l) return MAX;
 
		if(a <= l and r <= b) return min_v[i];
 
		eval(i);
		T lv = rangemin(i * 2 + 1, a, b, l, (l + r) >> 1);
		T rv = rangemin(i * 2 + 2, a, b, (l + r) >> 1, r);
		return std::min(lv, rv);
	}
 
	T rangemax(int i, int a, int b, int l, int r) {
		if(r <= a or b <= l) return MIN;
 
		if(a <= l and r <= b) return max_v[i];
 
		eval(i);
		T lv = rangemax(i * 2 + 1, a, b, l, (l + r) >> 1);
		T rv = rangemax(i * 2 + 2, a, b, (l + r) >> 1, r);
		return std::max(lv, rv);
	}
 
	T rangesum(int i, int a, int b, int l, int r) {
		if(r <= a or b <= l) return 0;
 
		if(a <= l and r <= b) return sigm[i];
 
		eval(i);
		T lv = rangesum(i * 2 + 1, a, b, l, (l + r) >> 1);
		T rv = rangesum(i * 2 + 2, a, b, (l + r) >> 1, r);
		return lv + rv;
	}
 
public:
	SegmentTreeBeats() = default;
 
	SegmentTreeBeats(std::vector<T> &v) {
		init(v);
	}
 
	SegmentTreeBeats(size_t n, T init_data = 0) {
		std::vector<T> v(n, init_data);
		init(v);
	}
 
	T operator[](int i) {
		return query_min(i, i + 1);
	}
 
	void update_chmin(int a, int b, T x) {
		chmin(0, a, b, 0, n, x);
	}
 
	void update_chmax(int a, int b, T x) {
		chmax(0, a, b, 0, n, x);
	}
 
	void update_add(int a, int b, T x) {
		add(0, a, b, 0, n, x);
	}
 
	void update_upd(int a, int b, T x) {
		update(0, a, b, 0, n, x);
	}
 
	T query_min(int a, int b) {
		return rangemin(0, a, b, 0, n);
	}
 
	T query_max(int a, int b) {
		return rangemax(0, a, b, 0, n);
	}
 
	T query_sum(int a, int b) {
		return rangesum(0, a, b, 0, n);
	}
};
#pragma endregion

void main_() {
	LL(N,Q);
	V<pair<ll,pll>> T(Q);
	REP(i,Q){
	    cin >> T[i].se.fi >> T[i].se.se >> T[i].fi;
	    T[i].se.fi--;
	}
	V<ll> ans(N,1);
	SegmentTreeBeats<ll> beats(ans);
	sort(all(T));
	REP(i,Q){
	    beats.update_chmax(T[i].se.fi,T[i].se.se,T[i].fi);
	}
	bool ok = true;
	REP(i,Q){
	    ll mn = beats.query_min(T[i].se.fi,T[i].se.se);
	    if(mn != T[i].fi)ok = false;
	}
	if(ok){
	    REP(i,N){
	        ll val = beats.query_min(i,i+1);
	        if(i)cout << " ";
	        cout << val;
	    }
	    cout << endl;
	}
	else cout << -1 << endl;
}
 
int main() {
	int t = 1;
	//cin >> t;
	while(t--) main_();
	return 0;
}