#include <bits/stdc++.h>
#include <atcoder/all>
using namespace std;
using namespace atcoder;
#define rep(i, n) for(int i=0;i<(n);++i)
#define rep1(i, n) for(int i=1;i<=(n);i++)
#define ll long long
using mint = modint998244353;
using P = pair<ll,ll>;
using lb = long double;
using T = tuple<ll, ll, ll>;
#ifdef LOCAL
#  include <debug_print.hpp>
#  define dbg(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#  define dbg(...) (static_cast<void>(0))
#endif

int main()
{
    int n, k;
    ll p;
    cin >> n >> p >> k;
    const ll INF = (ll)1e18 + 1;
    dbg(INF);
    vector<ll> dp(k+1, -INF);
    dp[0] = p;
    rep(i,n) {
        int t, b;
        cin >> t >> b;
        vector<ll> p(k+1, -INF);
        swap(dp, p);
        if(t==1){
            for(int j=0;j<=k;j++){
                dp[j] =  max(dp[j], p[j]);
                if(j+1<=k) dp[j+1] = max(dp[j+1], p[j]+b);
            }
        }
        else{
            for(int j=0;j<=k;j++){
                dp[j] =  max(dp[j], p[j]);
                if(j+1<=k) dp[j+1] = max(dp[j+1], p[j]*2);
            }
        }
        rep(j,k+1) dp[j] = min(dp[j],INF);
    }
    ll ans = dp[k];
    if(ans>=INF) ans = -1;
    cout << ans << endl;
    return 0;
}