#include <stdio.h>
#include <iostream>
using namespace std;
struct El {
    int data;
    El * next;
};
int countt = 0;
El * top = NULL;
El * createEl(int x) {
    El * t = new El();
    t->data = x;
    t->next = NULL;
    return t;
}
void push(int x) {
    El * t = createEl(x);
    if (top == NULL) {
        top = t;
        return;
    }
    t->next = top;
    top = t;
}
void pop() {
    if (top == NULL) return;
    top = top->next;
    if (countt > 0) countt = countt - top->data;
}
int main() {
    int n, Q, x;
    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> Q;
        if (Q == 0) {
            pop();
        }
        if (Q == 1) {
            cin >> x;
            push(x);
            countt += x;
        }
        if (Q == 2) {
            cout << countt << "\n";
        }
    }
    return 0;
}