#include <stdio.h>
int main()
{
int carry,i;
int n,count;
while (scanf("%d",&n)!=EOF)
{
carry=0;
count=0;
do
{
for (i=0;i<10;i++)
{
if ((carry+i*n)%10==1)
{
count++;
break;
}
}
carry=(carry+i*n)/10;
} while (carry);
printf("%d/n",count);
}
return 0;
}
注:简单的大数计算,开始时竟然没看出来