rt，考场样例全过但不知为何挂分

#include<bits/stdc++.h>
#define ll long long
using namespace std;
namespace abcdq{
	ll read(){
	   int x=0;char ch=getchar();
	   while(!isdigit(ch)) ch=getchar();
	   while(isdigit(ch)) x=x*10+ch-48,ch=getchar();
	   return x;
	}
	void write(ll x){
		 if(x>9) write(x/10);
		 putchar(x%10+48);
	}
	const int maxn=1e5+5;
	ll v[maxn],a[maxn];
	void main(){
	#ifndef DEBUG
		freopen("road.in","r",stdin);
		freopen("road.out","w",stdout);
	#endif
		ll n=read(),d=read(),sum=0;
		for(int i=1;i<n;i++)
            v[i]=read();
        for(int i=1;i<=n;i++)
            a[i]=read();
        ll minv=a[1],sheng=0;
        for(int i=1;i<n;i++){
        	minv=min(minv,a[i]);
            sum+=(((v[i]-sheng)/d)+(bool)((v[i]-sheng)%d))*minv;
            sheng=(((v[i]-sheng)/d)+(bool)((v[i]-sheng)%d))*d+sheng-v[i];
        }
        write(sum);
	}
}
int main(){
	abcdq::main();
}