The police department of your city has just started its journey. Initially, they don’t have any manpower. So, they started hiring new recruits in groups.

Meanwhile, crimes keeps occurring within the city. One member of the police force can investigate only one crime during his/her lifetime.

If there is no police officer free (isn't busy with crime) during the occurrence of a crime, it will go untreated.

Given the chronological order of crime occurrences and recruit hirings, find the number of crimes which will go untreated.
The first line of input will contain an integer *n* (1 ≤ *n* ≤ 10<sup class="upper-index">5</sup>), the number of events. The next line will contain *n* space-separated integers.

If the integer is -1 then it means a crime has occurred. Otherwise, the integer will be positive, the number of officers recruited together at that time. No more than 10 officers will be recruited at a time.
# Read the input values
n = int(input())
events = list(map(int, input().split()))

# Initialize variables
police_count = 0
untreated_crimes = 0

# Iterate through the events
for event in events:
    # Check if a crime has occurred
    if event == -1:
        # If there are no free police officers, increment the untreated crimes count
        if police_count == 0:
            untreated_crimes += 1
        # If there are free police officers, decrement the count
        else:
            police_count -= 1
    # If officers are recruited, add them to the police count
    else:
        police_count += event

# Print the number of untreated crimes
print(untreated_crimes)
