#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define rep(i,n) for (int i=0;i<(int)(n);i++)

int main(){
  int n,p,c;
  cin>>n>>p>>c;
  vector<int> v(n);
  vector<int> w(n);
  rep(i,n) cin>>v.at(i)>>w.at(i);
  vector<vector<vector<ll>>> dp(n+1,vector<vector<ll>>(n+1,vector<ll>(p+1,0)));
  rep(i,n){
    rep(k,n){
      rep(j,p){
        for(ll l=1;j+l*v.at(i)<=p;l++) dp[i+1][k+1][j+l*v.at(i)]=max(dp[i+1][k+1][j+l*v.at(i)],(dp[i][k][j]+l*w.at(i)+c));
        dp[i+1][k+1][j+1]=max(dp[i+1][k+1][j+1],dp[i][k+1][j+1]);
        dp[i+1][k+1][j+1]=max(dp[i+1][k+1][j+1],dp[i+1][k+1][j]);
      }
    }
    /*
    for(auto dd:dp.at(i+1)){
      for(auto d:dd) cout<<d<<" ";
      cout<<endl;
    }
    cout<<endl;
    */
  }
  ll ans=0;
  rep(k,n+1) ans=max(dp[n][k][p],ans);
  cout<<ans<<endl;
}