import sys
input = sys.stdin.readline
from collections import defaultdict 

# ACL for pythonより
# https://github.com/shakayami/ACL-for-python/blob/master/lazysegtree.py
class lazy_segtree():
    def update(self,k):self.d[k]=self.op(self.d[2*k],self.d[2*k+1])
    def all_apply(self,k,f):
        self.d[k]=self.mapping(f,self.d[k])
        if (k<self.size):self.lz[k]=self.composition(f,self.lz[k])
    def push(self,k):
        self.all_apply(2*k,self.lz[k])
        self.all_apply(2*k+1,self.lz[k])
        self.lz[k]=self.identity
    def __init__(self,V,OP,E,MAPPING,COMPOSITION,ID):
        self.n=len(V)
        self.log=(self.n-1).bit_length()
        self.size=1<<self.log
        self.d=[E for i in range(2*self.size)]
        self.lz=[ID for i in range(self.size)]
        self.e=E
        self.op=OP
        self.mapping=MAPPING
        self.composition=COMPOSITION
        self.identity=ID
        for i in range(self.n):self.d[self.size+i]=V[i]
        for i in range(self.size-1,0,-1):self.update(i)
    def set(self,p,x):
        assert 0<=p and p<self.n
        p+=self.size
        for i in range(self.log,0,-1):self.push(p>>i)
        self.d[p]=x
        for i in range(1,self.log+1):self.update(p>>i)
    def get(self,p):
        assert 0<=p and p<self.n
        p+=self.size
        for i in range(self.log,0,-1):self.push(p>>i)
        return self.d[p]
    def prod(self,l,r): #[l,r)の取得, [x,x)と取得すると単位元を返すので注意。
        assert 0<=l and l<=r and r<=self.n
        if l==r:return self.e
        l+=self.size
        r+=self.size
        for i in range(self.log,0,-1):
            if (((l>>i)<<i)!=l):self.push(l>>i)
            if (((r>>i)<<i)!=r):self.push(r>>i)
        sml,smr=self.e,self.e
        while(l<r):
            if l&1:
                sml=self.op(sml,self.d[l])
                l+=1
            if r&1:
                r-=1
                smr=self.op(self.d[r],smr)
            l>>=1
            r>>=1
        return self.op(sml,smr)
    def all_prod(self):return self.d[1]
    def apply_point(self,p,f):
        assert 0<=p and p<self.n
        p+=self.size
        for i in range(self.log,0,-1):self.push(p>>i)
        self.d[p]=self.mapping(f,self.d[p])
        for i in range(1,self.log+1):self.update(p>>i)
    def apply(self,l,r,f):  #[l,r)に作用
        assert 0<=l and l<=r and r<=self.n
        if l==r:return
        l+=self.size
        r+=self.size
        for i in range(self.log,0,-1):
            if (((l>>i)<<i)!=l):self.push(l>>i)
            if (((r>>i)<<i)!=r):self.push((r-1)>>i)
        l2,r2=l,r
        while(l<r):
            if (l&1):
                self.all_apply(l,f)
                l+=1
            if (r&1):
                r-=1
                self.all_apply(r,f)
            l>>=1
            r>>=1
        l,r=l2,r2
        for i in range(1,self.log+1):
            if (((l>>i)<<i)!=l):self.update(l>>i)
            if (((r>>i)<<i)!=r):self.update((r-1)>>i)
    def max_right(self,l,g):
        assert 0<=l and l<=self.n
        assert g(self.e)
        if l==self.n:return self.n
        l+=self.size
        for i in range(self.log,0,-1):self.push(l>>i)
        sm=self.e
        while(1):
            while(i%2==0):l>>=1
            if not(g(self.op(sm,self.d[l]))):
                while(l<self.size):
                    self.push(l)
                    l=(2*l)
                    if (g(self.op(sm,self.d[l]))):
                        sm=self.op(sm,self.d[l])
                        l+=1
                return l-self.size
            sm=self.op(sm,self.d[l])
            l+=1
            if (l&-l)==l:break
        return self.n
    def min_left(self,r,g):
        assert (0<=r and r<=self.n)
        assert g(self.e)
        if r==0:return 0
        r+=self.size
        for i in range(self.log,0,-1):self.push((r-1)>>i)
        sm=self.e
        while(1):
            r-=1
            while(r>1 and (r%2)):r>>=1
            if not(g(self.op(self.d[r],sm))):
                while(r<self.size):
                    self.push(r)
                    r=(2*r+1)
                    if g(self.op(self.d[r],sm)):
                        sm=self.op(self.d[r],sm)
                        r-=1
                return r+1-self.size
            sm=self.op(self.d[r],sm)
            if (r&-r)==r:break
        return 0

def operate(x,y):
    return min(x,y)
def mapping(f,x): #LAZYの部分に(x,y)という値を保存する。ただ足すだけならx=1でyを足すということか。
    return f[0]*x+f[1]
def composition(f,g):
    return (f[0]*g[0],g[1]*f[0]+f[1])

class SegmentTree(object):
    def __init__(self, A, dot, unit):
        n = 1 << (len(A) - 1).bit_length()
        tree = [unit] * (2 * n)
        for i, v in enumerate(A):
            tree[i + n] = v
        for i in range(n - 1, 0, -1):
            tree[i] = dot(tree[i << 1], tree[i << 1 | 1])
        self._n = n
        self._tree = tree
        self._dot = dot
        self._unit = unit

    def __getitem__(self, i):
        return self._tree[i + self._n]

    def update(self, i, v):
        i += self._n
        self._tree[i] = v
        while i != 1:
            i >>= 1
            self._tree[i] = self._dot(self._tree[i << 1], self._tree[i << 1 | 1])

    def add(self, i, v):
        self.update(i, self[i] + v)

    def sum(self, l, r): #これで[l,r)から取り出す。
        l += self._n
        r += self._n
        l_val = r_val = self._unit
        while l < r:
            if l & 1:
                l_val = self._dot(l_val, self._tree[l])
                l += 1
            if r & 1:
                r -= 1
                r_val = self._dot(self._tree[r], r_val)
            l >>= 1
            r >>= 1
        return self._dot(l_val, r_val)

def main():
    N,Q = map(int,input().split()); INF = pow(10,9)
    L = defaultdict(list)
    R = defaultdict(list)
    comp = set([])
    query = []
    for i in range(Q):
        l,r,b = map(int,input().split())
        l -= 1; r -= 1
        L[l].append(b)
        R[r].append(b)
        comp.add(b)
        query.append((l,r,b))

    query.sort(key = lambda x:x[2])
    G = lazy_segtree([INF for i in range(N)],operate,INF,mapping,composition,(1,0))
    for l,r,b in query:
        G.apply(l,r+1,(0,b))
    
    ans = [INF]*N
    for i in range(N):
        ans[i] = G.get(i)
    
    #print(*ans)

    Tree = SegmentTree(ans,min,INF)
    for l,r,b in query:
        mx = Tree.sum(l,r+1)
        if mx != b:
            print(-1)
            break
    else:
        print(*ans)



    
if __name__ == '__main__':
    main()