Same logic (thanks!) with constraits addressed.

def algoCrush():

    try:
        listSize, opsCount = map(int, raw_input().split())
    except:
        return None
    #constraint 1 and 2
    if not all([listSize >=3, listSize <= 10**7, opsCount >= 1, opsCount <= 2*10**5]):
        return None

    crushList = [0]*listSize
    for _ in range(opsCount):
        try:
            start, end, addnum = map(int, raw_input().split())
        except:
            return None
        #constraint 3 and 4
        if not all([start >= 1, start <= end, end <= listSize, addnum >= 0, addnum <= 10**9]):
            return None
        crushList[start-1] += addnum
        if end <= (listSize -1):
            crushList[end] -= addnum
    prev = high = 0
    for i in range(listSize):         
        prev += crushList[i]
        if  high < prev:
            high = prev
    print high


algoCrush()




For instance, when list size less than 3, it should not     return any thing.
2 3
1 2 3
1 2 3
1 2 3
9    -----> should have failed.

Likewise, when there are strings in numbers.
2 3
1 2 3
1 2 3
1 2 str
Traceback (most recent call last):
File "a.py", line 4, in <module>
a, b, k = [int(n) for n in raw_input().split() ]
ValueError: invalid literal for int() with base 10: 'str'