1231 The Embarrassed Cryptography

/* source code of submission 435783, Zhongshan University Online Judge System */
#include <stdio.h>
#include <memory.h>
#include <string.h>
const int p10[]={1,10,100,1000};
const int N=1000000;
bool isprime[N+1];
char K[102];
int  hp[40];
int  L,len;
int  ans;
void  makeprime()
{
memset(isprime, true, sizeof(isprime) );
for (int i=2; i<=N; ++i )
{
if ( isprime[i] )
{
for (int j=2; j*i<=N; ++j)
{
isprime[j*i]=false;
}
}
}
}
void trans()
{
memset(hp, 0, sizeof(hp) );
len=(strlen(K)-1)/3;
int slen=strlen(K);
for (int i=0; i<=len; ++i)
{
for (int j=1; j<=3 && slen-i*3-j>=0; ++j)
{
hp[i]+=p10[j-1]*(K[slen-i*3-j]-'0');
}
}
}
bool module(int x)
{
int ret=0;
for (int i=len; i>=0; --i)
{
ret=(hp[i]+ret*1000)%x;
}
return ret;
}
bool check()
{
for (int i=2; i<L; ++i)
{
if ( !isprime[i] )
{
continue;
}

if ( module(i)==0 )
{
ans=i;
return false;
}
}
return true;
}
int main(int argc, char *argv[])
{
makeprime();
while ( scanf("%s%d",K, &L)&& L!=0 )
{
trans();
if ( check() )
{
printf("GOOD/n");
}
else
{
printf("BAD %d/n",ans);
}
}
return 0;
}