import java.util.*;

public class App {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);

        String[] temp = sc.nextLine().split(" ");
        int N = Integer.parseInt(temp[0]);//アイテムの個数
        int P = Integer.parseInt(temp[1]);//剣の攻撃力
        int K = Integer.parseInt(temp[2]);//装備するアイテム
        int T , B , _Max_Power = 0;
        String[] _attack_power = new String[N];
        for(int i = 0; i < N; i++){
            _attack_power[i] = sc.nextLine();
        }
        for(int i = 0; i <= N - K; i++){
            int _attack_power_count = P;
            for(int j = 0 + i; j < K + i; j++){
                String[] item_type =  _attack_power[j].split(" ");
                T = Integer.parseInt(item_type[0]);
                B = Integer.parseInt(item_type[1]);
                if(T == 1){
                    _attack_power_count += B;
                }
                else if(T == 2){
                    _attack_power_count = _attack_power_count * 2;
                }
            }
            if(_attack_power_count > _Max_Power){
                _Max_Power = _attack_power_count;
            }  
        }
        System.out.println(_Max_Power);
    }
}