local int = require "int"
local fmt = require "fmt"

local limit <const> = 1e9
local gap_starts = {}
local primes = int.primes(limit * 5, true, 128 * 1024)
for i = 2, #primes do
    local gap = primes[i] - primes[i - 1]
    if !gap_starts[gap] then gap_starts[gap] = primes[i - 1] end
end
local pm = 10
local gap1 = 2
while true do
    while !gap_starts[gap1] do gap1 += 2 end
    local start1 = gap_starts[gap1]
    local gap2 = gap1 + 2
    if !gap_starts[gap2] then
        gap1 = gap2 + 2
        continue
    end
    local start2 = gap_starts[gap2]
    local diff = math.abs(start2 - start1)
    if diff > pm then
        fmt.print("Earliest difference > %,s between adjacent prime gap starting primes:", pm)
        fmt.print("Gap %d starts at %,s, gap %d starts at %,s, difference is %,s.\n", gap1, start1, gap2, start2, diff)
        if pm == limit then break end
        pm *= 10
    else
        gap1 = gap2
    end
end