include<bits/stdc++.h>
using namespace std;
int a[100001];
int main(){

        int n;
        cin>>n;
        for(int i=0;i<n;i++){
            cin>>a[i];
        }
        int i=0;
        int cnt=0;
        vector<int>v,ans;
        set<int>pos,neg;
        while(i<n){

            int val=a[i];
            if(val>0){

                if(pos.count(val)||neg.count(val)){
                    cout<<"-1"<<endl;
                    return 0;
                }
                pos.insert(val);
                cnt++;
            }
            else{
                val=-val;
                if(!pos.count(val)||neg.count(val)){
                    cout<<"-1"<<endl;
                    return 0;
                }
                neg.insert(val);
                --cnt;
            }
            i++;
            v.push_back(val);
            if(cnt==0){
                ans.push_back(v.size());
                v.clear();
                pos.clear();
                neg.clear();
            }
        }
        if(v.size()){
            cout<<"-1"<<endl;
            return 0;
        }
        cout<<ans.size()<<endl;
        for(int i=0;i<ans.size();i++){
            cout<<ans[i]<<" ";
        }


     return 0;
}