This is my program:

#include <stdio.h>
int len[16];
int ldist[16];
int rdist[16];
int depart;
int gor,gol,iv;
int N;
void prelr()
{
    int i;
    ldist[0]=0;
    for (i=1;i<N;i++)
        ldist[i]=ldist[i-1]+len[i-1];
    for (i=N-2;i>=0;i--)
        rdist[i]=rdist[i+1]+len[i];
}
void read()
{
    scanf("%d",&N);
    int i;
    for (i=0;i<N-1;i++)
        scanf("%d",&len[i]);
    scanf("%d",&depart);
    depart--;
    scanf("%d%d%d",&iv,&gor,&gol);
}
int best;
bool first;
int deptime;
void nexttimepoint(int&time,int&posi,int&dir)
{
    //Test nearest shuttle
    int tmp;
    if (dir==1)
    {
        tmp=((time-ldist[posi]-gor)%iv+iv)%iv;
        if (tmp!=0) tmp=iv-tmp;
        time+=tmp;
    }
    else
    {
        tmp=((time-rdist[posi]-gol)%iv+iv)%iv;
        if (tmp!=0) tmp=iv-tmp;
        time+=tmp;
    }
    //Record if it's first
    if (first)
    {
        first=false;
        deptime=time;
    }

    //Make path
    if (dir==1)
    {
        time+=len[posi];
        posi++;
    }
    else
    {
        time+=len[posi-1];
        posi--;
    }

    //Test if reverse needed
    if (posi==0)
        dir=1;
    if (posi==N-1)
        dir=-1;

}
void testdepart(int direct)
{
    int i,time,p,delayi,dir;
    int last;
    for (i=1<<(N-2);i-->0;)
    {
        delayi=i;
        last=(1<<N)-1;
        if (direct==1)
            time=ldist[depart];
        else
            time=rdist[depart];
        p=i;
        dir=direct;
        p=depart;
        first=true;
        nexttimepoint(time,p,dir);
        while (p!=depart||dir!=direct)
        {
            if (p==0||p==N-1)
                time++;
            else if (last&(1<<p)&&p!=depart)
            {
                if (delayi&(1<<(p-1)))
                    delayi^=1<<(p-1);
                else
                {
                    last^=1<<p;
                    time++;
                }
            }
            nexttimepoint(time,p,dir);
        }
        if (best>time-deptime)
            best=time-deptime;
    }
}
void process()
{
    prelr();
    if (depart!=N-1)
        testdepart(1);
    if (depart!=0)
        testdepart(-1);
}
int main()
{
    read();
    best=2147483647;
    if (N==1)
        printf("0\n");
    else
        process();
    printf("%d\n",best);
    return 0;
}

Thanks.