#!/usr/bin/env python3

def divisors(divs):
    r = []
    for p in divs:
        r += [p*d for d in r] + [p]
    return r

def add_divisors(n, st=2):
    for i in range(st*n, len(sieve), st*n):
        sieve[i].append(n)
    pw = 2
    while n**pw < len(sieve):
        m = n**pw
        for i in range(st*m, len(sieve), st*m):
            sieve[i][-1] *= n
        pw += 1

target = 25
count = 0
s = 0

lim = 10**5
sieve = [x for i in range(lim//2) for x in ([], True)]

add_divisors(2, st=1)

for p in range(3, len(sieve)):
    if not p%2 and not sieve[p+1]:
        for d in divisors(sieve[p]):
            if pow(10, d, 9*p+9) == 1:
                break
        else:
            continue
        count += 1
        s += p + 1
        #print(count, p+1)
        if count >= target:
            break
    if not p%2 or not sieve[p]:
        continue
    for i in range(p**2, len(sieve), 2*p):
         sieve[i] = False
    add_divisors(p)

if count < target:
    print("Limit reached. Count = {}/{}".format(count,target))

print(s)