class LazySegTree: # RMQ and RUQ def __init__(self, init_val, seg_ide, lazy_ide, segfunc): self.n = len(init_val) self.num = 2**(self.n-1).bit_length() self.seg_ide = seg_ide self.lazy_ide = lazy_ide self.segfunc = segfunc # seg, lazy: 1-indexed self.seg = [seg_ide]*2*self.num for i in range(self.n): self.seg[i+self.num] = init_val[i] for i in range(self.num-1, 0, -1): self.seg[i] = self.segfunc(self.seg[2*i], self.seg[2*i+1]) self.lazy = [lazy_ide]*2*self.num def gindex(self, l, r): # l, r: 1-indexed L = l + self.num R = r + self.num lm = (L // (L & -L)) >> 1 rm = (R // (R & -R)) >> 1 while L < R: if R <= rm: yield R if L <= lm: yield L L = L >> 1 R = R >> 1 while L: yield L L = L >> 1 def propagate(self, *ids): # ids: 1-indexed for i in reversed(ids): v = self.lazy[i] if v is None: continue self.lazy[2*i] = self.lazy[2*i+1] = self.seg[2*i] = self.seg[2*i+1] = v self.lazy[i] = None def update(self, l, r, x): # l, r: 0-indexed # change x to [l, r) *ids, = self.gindex(l, r) self.propagate(*ids) L = l + self.num R = r + self.num while L < R: if R & 1: R -= 1 self.lazy[R] = self.seg[R] = x if L & 1: self.lazy[L] = self.seg[L] = x L += 1 L = L >> 1 R = R >> 1 for i in ids: # i: 1-indexed self.seg[i] = self.segfunc(self.seg[2*i], self.seg[2*i+1]) def query(self, l, r): # l, r: 0-indexed # query for [l, r) if r <= l: return self.seg_ide self.propagate(*self.gindex(l, r)) L = l + self.num R = r + self.num res = self.seg_ide while L < R: if R & 1: R -= 1 res = self.segfunc(res, self.seg[R]) if L & 1: res = self.segfunc(self.seg[L], res) L += 1 L = L >> 1 R = R >> 1 return res def __str__(self): # for debug arr = [self.query(i,i+1) for i in range(self.n)] return str(arr) class SegTree: def __init__(self, init_val, ide_ele, segfunc): self.n = len(init_val) self.num = 2**(self.n-1).bit_length() self.ide_ele = ide_ele self.segfunc = segfunc self.seg = [ide_ele]*2*self.num # set_val for i in range(self.n): self.seg[i+self.num] = init_val[i] # built for i in range(self.num-1, 0, -1): self.seg[i] = self.segfunc(self.seg[2*i], self.seg[2*i+1]) def update(self, k, x): k += self.num self.seg[k] = x while k: k = k >> 1 self.seg[k] = self.segfunc(self.seg[2*k], self.seg[2*k+1]) def query(self, l, r): if r <= l: return self.ide_ele l += self.num r += self.num lres = self.ide_ele rres = self.ide_ele while l < r: if r & 1: r -= 1 rres = self.segfunc(self.seg[r], rres) if l & 1: lres = self.segfunc(lres, self.seg[l]) l += 1 l = l >> 1 r = r >> 1 res = self.segfunc(lres, rres) return res def __str__(self): # for debug arr = [self.query(i,i+1) for i in range(self.n)] return str(arr) def segfunc(x, y): if x <= y: return x else: return y INF = 10**18 import sys import io, os input = io.BytesIO(os.read(0,os.fstat(0).st_size)).readline def main(): n, q = map(int, input().split()) LR = [0]*q for i in range(q): l, r, b = map(int, input().split()) l, r = l-1, r-1 LR[i] = (l, r, b) seg = LazySegTree([INF]*n, INF, None, segfunc) LR.sort(key=lambda x: x[2]) #print(LR) for l, r, b in LR: seg.update(l, r+1, b) A = [INF]*n for i in range(n): a = seg.query(i, i+1) if a == INF: A[i] = 10**9 else: A[i] = a seg = SegTree(A, INF, segfunc) for l, r, b in LR: x = seg.query(l, r+1) if x != b: print(-1) exit() else: print(*A) if __name__ == '__main__': main()