1)
t = int(input())
v = int(input())
print(t * v + t / 2 * v / 2, 'км')
2)
p = int(input())
x = int(input())
y = int(input())
if p < 0:
m = x + y
print(m)
else:
m = x - y
print(m)
3)
sm = 0
for i in range(10, 100):
if i % 3 == 0:
sm += i
print(sm)
4)
a = int(input())
for x in range(3, 16, 3):
print(a + 2 * x)