Buggy python submission (verdict: Runtime Error):
# coding: utf-8
# Your code here!

import sys
sys.setrecursionlimit(10**6)
readline = sys.stdin.readline 

n = int(input())
a = [int(i) for i in readline().split()]
b = [int(i) for i in readline().split()]
pb = [(bi,i) for i,bi in enumerate(b)]

sa = sorted(a)
sb = sorted(b)
pb.sort()

na = [a[i] for bi,i in pb]


ok = 1
for i,j in zip(sa,sb):
    if i > j: ok = 0

for i,j in zip(sa[1:],sb):
    if i <= j: break
else:
    #sa => na が巡回置換か？
    d = {ai:i for i,ai in enumerate(sa)}
    ra = [d[ai] for ai in na]
    
    #print(ra,ok)    
    now = 0
    for i in range(n-1):
        now = ra[now]
        #print(now)
        if now == 0:
            break
    else: ok = 0    


    

#print(a,b,sa,sb,na)

if ok: print("Yes")    
else: print("No")
    
    
    
    
    
    

Fixed submission:
"""
双対セグ木
アクセスは0-indexed, 内部のツリーは 1-indexed
つまりすべての和は tree[0]
関数は閉区間
作用素は右から作用とする

引数：
    N: 処理する区間の長さ
    compose: 作用素を合成させる関数 (max, min, __add__,ラムダ式,関数定義など)
    UNIT: 恒等作用素
    funcval(x,f) = f(x)
"""

class segment_tree:
    def __init__(self, N, compose, funcval, UNIT=None):
        self.compose = compose
        self.UNIT = UNIT
        self.funcval = funcval

        self.h = (N-1).bit_length() #木の高さ
        self.N0 = 1<<self.h #木の横幅 >= N
        self.laz = [self.UNIT]*(2*self.N0) #作用素の木
        self.val = None #値の配列

    #初期値の配列を作る
    def build(self,initial):
        self.val = initial[:]

    #laz[k] を子に伝える、
    def propagate(self,k):
        if self.laz[k] == self.UNIT: return;
        if self.N0 <= k:
            self.val[k-self.N0] = self.funcval(self.val[k-self.N0], self.laz[k])
            self.laz[k] = self.UNIT
        else:
            self.laz[(k<<1)  ] = self.compose(self.laz[(k<<1)  ],self.laz[k]);
            self.laz[(k<<1)+1] = self.compose(self.laz[(k<<1)+1],self.laz[k]);
            self.laz[k] = self.UNIT;
    
    # laz[k]およびその上に位置する作用素をすべて伝播
    def thrust(self,k):
        for i in range(self.h,-1,-1): self.propagate(k>>i)

    # 区間[l,r]に関数 f を作用
    def update(self, L,R,f):
        L += self.N0; R += self.N0+1
        """まず伝播させる（オペレータが可換なら必要ない）"""
        self.thrust(L)
        self.thrust(R-1)
        #登りながら関数 f を合成
        while L < R:
            if R & 1:
                R -= 1
                self.laz[R] = self.compose(self.laz[R],f)
            if L & 1:
                self.laz[L] = self.compose(self.laz[L],f)
                L += 1
            L >>= 1; R >>= 1
    
    # values[k] を取得。
    def point_get(self, k):
        res = self.val[k]
        k += self.N0
        while k:
            res = self.funcval(res, self.laz[k])
            k //= 2
        return res
    
    # values[k] = x 代入する
    def point_set(self, k): 
        self.thrust(k)
        values[k] = x



###########################################################################
#日経2020予選D

###########################################################################

# coding: utf-8
# Your code here!
 
import sys
sys.setrecursionlimit(10**6)
readline = sys.stdin.readline 

n,m = [int(i) for i in readline().split()]
lrc = [tuple(int(i) for i in readline().split()) for _ in range(m)]
lrc.sort()

compose = lambda f,g: min(f,g)
funcval = lambda x,f: min(x,f)
UNIT = INF = 10**18

seg = segment_tree(n, compose, funcval, UNIT)
seg.build([0]+[INF]*(n-1))

for l,r,c in lrc:
    l -= 1
    r -= 1
    v = seg.point_get(l)
    seg.update(l+1,r,v+c)

ans = seg.point_get(n-1)

if ans != INF:
    print(ans)
else:
    print(-1)