import math
def giaithua(x):
a = 1
for i in range(1, x + 1):
a = a * i
return a
n = int(input())
print(giaithua(n))
aW1wb3J0IG1hdGgKCmRlZiBnaWFpdGh1YSh4KToKCWEgPSAxCglmb3IgaSBpbiByYW5nZSgxLCB4ICsgMSk6CgkJYSA9IGEgKiBpCglyZXR1cm4gYQoKbiA9IGludChpbnB1dCgpKQpwcmludChnaWFpdGh1YShuKSk=