#include <iostream>
#include <map>

using namespace std;

map<int, int> m;
int _offset = 0;

int value(int key)
{
    return m[key] + _offset;
}

void insert(int key, int value)
{
    m[key] = value - _offset;
}

void remove(int key)
{
    m.erase(key);
}

void inc(int key, int offset)
{
    m[key] += offset;
}

void inc_all(int offset)
{
    _offset += offset;
}