#include <iostream>
#include <vector>
#include <map>
#include <algorithm>
using namespace std;

map <int, int> a;
int n;

int main()
{
    ios_base::sync_with_stdio(false);
    cin >> n;
    char last = 0;
    int lastans = -1;

    for(int i = 1; i <= n; i++){
        char foo;
        int bar;
        cin >> foo >> bar;
        if(foo == '?'){
            auto next = a.lower_bound(bar);
            if( (next->second) == 0 ){
                cout << -1;
                lastans = -1;
            } else{
                cout << next->second;
                lastans = next->second;
            }
            cout << endl;
        } else{
            if(last == '?' && lastans != -1){
                a[(bar + lastans) % (int)1e9] = (bar + lastans) % (int)1e9;
            } else{
                a[bar] = bar;
            }
        }
        last = foo;
    }
}