#include "isprime.bas"

function nextprime( n as uinteger ) as uinteger
    'finds the next prime after n, excluding n if it happens to be prime itself
    if n = 0 then return 2
    if n < 3 then return n + 1
    dim as integer q = n + 2
    while not isprime(q)
        q+=2
    wend
    return q
end function

function lastprime( n as uinteger ) as uinteger
    'finds the last prime before n, excluding n if it happens to be prime itself
    if n = 2 then return 0       'zero isn't prime, but it is a good sentinel value :)
    if n = 3 then return 2
    dim as integer q = n - 2
    while not isprime(q)
        q-=2
    wend
    return q
end function

function isstrong( p as integer ) as boolean
    if nextprime(p) + lastprime(p) >= 2*p then return false else return true
end function

function isweak( p as integer ) as boolean
    if nextprime(p) + lastprime(p) <= 2*p then return false else return true
end function

print "The first 36 strong primes are: "
dim as uinteger c, p=3
while p < 10000000
    if isprime(p) andalso isstrong(p) then
        c += 1
        if c <= 36 then print p;" ";
        if c=37 then print
    end if
    if p = 1000001 then print "There are ";c;" strong primes below one million"
    p+=2
wend
print "There are ";c;" strong primes below ten million"
print

print "The first 37 weak primes are: "
p=3 : c=0
while p < 10000000
    if isprime(p) andalso isweak(p) then
        c += 1
        if c <= 37 then print p;" ";
        if c=38 then print
    end if

    if p = 1000001 then print "There are ";c;" weak primes below one million"
    p+=2
wend
print "There are ";c;" weak primes below ten million"
print