n,p=map(int,input().split())
s=list(map(int,input().split()))
l1=len(s)
d=[0]*(l1+1)
for i in range(1,l1+1):
    if i==1:
        d[i]=s[0]
    else:
        d[i]=s[i-1]-s[i-2]
for i in range(0,p):
    L,R,value=map(int,input().split())
    if R+1<=(len(d)-1):
        d[L]+=value
        d[R+1]-=value
    else:d[L]+=value
min=temp=d[1]
for i in range(2,l1+1):
    temp+=d[i]
    if temp<=min:
        min=temp
print(min)