import sys
line = input()
line = line.strip().split(" ")
if len(line) > 1:
    print(int(line[0]) + int(line[1]))
    line = input()
    print(line.strip())
    sys.exit()
else:
    line = line[0]
try:
    n = int(line)
except Exception as e:
    print("Hello World!")
    sys.exit()
sum = 0
cnt = 0
try:
    while True:
        s = int(input())
        sum += s
except Exception as e:
    if cnt == 0:
        print(int(n * (n + 1) / 2))
    else:
        print(int(s))