public static void main(String[] args) {
Scanner scanner = new Scanner(System.in);
int n = scanner.nextInt();
int[][] opers = new int[n][2];
boolean[] map = new boolean[100];
ArrayList<int[]> res = new ArrayList<>();
ArrayList<Object> res1 = new ArrayList<>();
for (int i = 0; i < n; i++) {
String line = scanner.next();
String oper = line.split("=")[0];
int size = Integer.parseInt(line.split("=")[1]);
if (oper.equals("REQUEST")) {
// 新增
int[] r = add(size, map, 1, 0, 0);
if (r[2] == -1) {
res1.add("error");
}else {
res1.add(r[0]);
}
res.add(r);
} else {
int index = size;
int len = -1;
for (int[] r :
res) {
if (r[0] == index) {
len = r[1];
release(size, map, len);
}
}
if (len == -1){
res1.add("error");
}
}
}
}
private static void release(int index, boolean[] map, int len) {
for (int i = 0; i < len; i++) {
map[i+index] = false;
}
}
private static int[] add(int size, boolean[] map, int len, int head, int current) {
if (size < len) {
return new int[]{head, head + len -1, 1};
}
if (current > map.length) {
release(head,map,len);
return new int[]{head, current, -1};
}
if (len > 1 && map[current]){
release(head,map,len);
len=1;
}
if (map[current]) {
head = current;
if (!map[current+1]){
head++;
}
}
if (!map[current]) {
len++;
map[current] = true;
}
return add(size, map, len, head, current + 1);
} 
