def my_mma022A_function():
    lines = []
    while True:
        line = input()
        if line == "":
            break
        lines.append(line)

    items = " ".join(lines).split()

    N = int(items[0])
    X = int(items[1])
    sum = 0
    for i in range(2, len(items)):
        sum += int(items[i])

    answer = sum - X

    if answer < 0 :
        answer = 0

    print(answer)

if __name__ == '__main__':
    my_mma022A_function()