package main

import (
    "fmt"
    "math/big"
)

var b = new(big.Int)

func isSPDSPrime(n uint64) bool {
    nn := n
    for nn > 0 {
        r := nn % 10
        if r != 2 && r != 3 && r != 5 && r != 7 {
            return false
        }
        nn /= 10
    }
    b.SetUint64(n)
    if b.ProbablyPrime(0) {