class TimeMap {
public:
    /** Initialize your data structure here. */
    std::unordered_map<std::string,std::map<int,string>> timeMap;
    TimeMap() {

    }

    void set(string key, string value, int timestamp) {
        timeMap[key][timestamp]=value;
    }

    string get(string key, int timestamp) {
        if (timeMap.find(key)==timeMap.end())
            return "";
        auto it = std::lower_bound(timeMap[key].begin(), timeMap[key].end(), timestamp, [](const auto& a, const auto& b)->bool{return a.first<b;});
        if (it==timeMap[key].begin())
            return "";
        if (it==timeMap[key].end())
            it--;
        return it->second;
    }
};

/**
 * Your TimeMap object will be instantiated and called as such:
 * TimeMap* obj = new TimeMap();
 * obj->set(key,value,timestamp);
 * string param_2 = obj->get(key,timestamp);
 */