uva11093 Just Finish it up

#include<bits/stdc++.h>
#define REP(i,a,b) for(int i=a;i<=b;i++)
#define MS0(a) memset(a,0,sizeof(a))

using namespace std;

typedef long long ll;
const int maxn=1000100;
const int INF=1<<29;

int n;
ll p[maxn],q[maxn];

int main()
{
    freopen("in.txt","r",stdin);
    int T;cin>>T;int casen=1;
    while(T--){
        scanf("%d",&n);
        REP(i,0,n-1) scanf("%lld",&p[i]);
        REP(i,0,n-1) scanf("%lld",&q[i]);
        int st=0,ans=-1;
        while(st<n){
            ll s=0;
            bool flag=1;
            int k=0;
            REP(j,0,n-1){
                s+=p[(st+j)%n];
                //cout<<st+j<<endl;
                //cout<<"s="<<s<<" "<<q[(st+j)%n]<<endl;
                if(s>=q[(st+j)%n]) s-=q[(st+j)%n];
                else{
                    k=j;
                    flag=0;break;
                }
            }
            //cout<<"st="<<st<<" flag="<<flag<<endl;
            if(flag){
                ans=st+1;break;
            }
            st=st+k+1;
        }
        printf("Case %d: ",casen++);
        if(ans==-1) puts("Not possible");
        else printf("Possible from station %d\n",ans);
    }
    return 0;
}
/**
why am I so stupid???!!!
*/