Codeforces #330 B Pasha and Phone

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll modd=1000000007;
ll a[100010],b[100010];
int n,k;
int main()
{
    while(scanf("%d%d",&n,&k)!=EOF)
    {
        for(int i=1; i<=n/k; i++)
            scanf("%I64d",&a[i]);
        for(int i=1; i<=n/k; i++)
            scanf("%I64d",&b[i]);
        ll cnt,sum=1;int uu=1;
        for(int i=0;i<k;i++)
        {
            uu*=10;
        }
        for(int i=1; i<=n/k; i++)
        {
            cnt=(uu-1)/a[i]+1;
            //printf("%d ",cnt);
            if(b[i]!=0)
            {
                ll x=((uu/10)*(b[i]+1)-1)/a[i];
                ll y=((uu/10)*b[i]-1)/a[i];
                //printf("%d %d ",x,y);
                cnt=cnt-(x-y);
            }
            else
            {
                ll x=(uu/10-1)/a[i];
                cnt=cnt-x-1;
                //printf("%d ",x);
            }
            //printf("%d\n",cnt);
            sum=(sum*cnt)%modd;

        }
        printf("%d\n",sum);
    }
    return 0;
}