题目链接：http://codeforces.com/contest/595/problem/B
题意：给你ai和bi，让你找到有多少个k位数，使得这个k位数不以bi开头且mod ai=0，处理n/k次，然后把所有的答案都乘起来
解法：容斥水题，所有的方案数 - 以bi开头的就好了

//CF 595B

#include <bits/stdc++.h>
using namespace std;
const int maxn = 100005;
const int mod = 1e9+7;
long long a[maxn], b[maxn];
long long ten[20];
long long ans[maxn];
int main()
{
    int n, k;
    scanf("%d%d", &n, &k);
    for(int i = 1; i <= n/k; i++) scanf("%lld", &a[i]);
    for(int i = 1; i <= n/k; i++) scanf("%lld", &b[i]);
    ten[0] = 1;
    for(int i = 1; i <= 10; i++) ten[i] = ten[i-1]*10;
    long long tmp1, tmp2, tmp3;
    for(int i = 1; i <= n/k; i++){
        tmp1 = (ten[k]-1)/a[i]+1;
        tmp2 = ((b[i]+1)*ten[k-1]-1)/a[i]+1;
        if(b[i] == 0) ans[i] = tmp1-tmp2;
        else{
            tmp3 = (b[i]*ten[k-1]-1)/a[i]+1;
            ans[i]=tmp1-tmp2+tmp3;
        }
    }
    long long Ans = 1;
    for(int i = 1; i <= n/k; i++){
        Ans = Ans*ans[i]%mod;
    }
    printf("%lld\n", Ans);
    return 0;
}