with open('fact.in', 'r') as f:
    nr= int(f.readline())

def finalZ(n):
    total = 0
    while n%10 == 0:
        total+=1
        n = n/10
    return total

def finalnZ(n):
    total = 0
    while n%10 == 0:
        n = n/10
    return n%10

lastnz = 1
totalz = 0
n = 2

while totalz < nr:
    #lastdigit = lastnz*n
    #totalz += finalZ(lastdigit)
    #lastnz = finalnZ(lastdigit)
    if n % 25 ==0:
        totalz+=2
    elif n % 5 == 0:
        totalz+=1
    n+=1

with open("fact.out", 'w') as g:
    g.write(str(n-1))