这怎么会是0分？洛谷是不是搞错了？朋友们帮我看一下，谢谢！

#include <iostream>
using namespace std;
int A[21];
int B[21];
int C[21];
int D[21];
int main()
{
    int a,b,c,d,ans=0;
    cin>>a>>b>>c>>d;
    cin>>A[1];
    for(int i=2;i<=a;i++)
    {
        cin>>A[i];
        ans+=min(A[i-1],A[i]);
        A[i]=abs(A[i-1]-A[i]);
    }
    ans+=A[a];

    cin>>B[1];
    for(int i=2;i<=b;i++)
    {
        cin>>B[i];
        ans+=min(B[i-1],B[i]);
        B[i]=abs(B[i-1]-B[i]);
    }
    ans+=B[b];

    cin>>C[1];
    for(int i=2;i<=c;i++)
    {
        cin>>C[i];
        ans+=min(C[i-1],C[i]);
        C[i]=abs(C[i-1]-C[i]);
    }
    ans+=C[c];

    cin>>D[1];
    for(int i=2;i<=d;i++)
    {
        cin>>D[i];
        ans+=min(D[i-1],D[i]);
        D[i]=abs(D[i-1]-D[i]);
    }
    ans+=D[d];
    cout<<ans;
}