#include <bits/stdc++.h>
using namespace std;

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    long long N,P,K; cin >> N >> P >> K;
    vector<long long> dp(K+1,-1e18);
    dp.at(0) = P;
    bool inf = false;
    for(int i=0; i<N; i++){
        int t,b; cin >> t >> b;
       
        vector<long long> next = dp;
        if(t == 1) for(int k=0; k<K; k++) next.at(k+1) = max(next.at(k+1),dp.at(k)+b);
        if(t == 2) for(int k=0; k<K; k++) next.at(k+1) = max(next.at(k+1),dp.at(k)*2);

        for(auto n : next) if(n > 1e18) n = 1e18+1;
        swap(next,dp);
    }
    if(dp.at(K) > 1e18) cout << -1 << endl;
    else cout << dp.at(K) << endl;
}