以下便是了：


#include<stdio.h>
#include<ctype.h>

int join(int array[],int count);
int factor(int n);

int main(void)
{
    int array[100];
    char n;
    int num,i,count;
    while(getchar()!='\n')
    {
        for(count=0,i=0;i<100;)
        {
            n=getchar();
            if(isdigit(n))
            {
                array[i]=(int)(n-'0');
                count++;
                i++;
            }
            if(n=='\n')
            break;
        }
        num=join(array,count);
        if(num==0)
        printf("0\n");
        else
        printf("%d\n",factor(num));
    }
    return 0;
}
int join(int array[],int count)
{
    int i,sum=0;
    for(i=0;i<count;i++)
    sum=sum*10+array[i];
    return sum;
}
int factor(int n)
{
    int j;
    if(n==1)
        return n;
    for(j=n-1;j>1;j--)
    {
        if(n%j==0)
        break;
    }
    if(j==1)
        return n;
    else
        return j;
}