fn main() {
    let (n, v, c) : (usize,usize,usize) = input_t3();

    let mut dp = vec![0; v+1];
    for _ in 0..n {
        let (vi, wi) : (usize, usize) = input_t();
        let mut next = vec![0; v+1];
        for i in 0..=v {
            chmax(dp[i], &mut next[i]);
            if i + vi > v  { continue }
            let d = (dp[i] + wi + c).max(next[i] + wi);
            chmax(d, &mut next[i+vi]);
        }
        dp = next;
    }

    if let Some(ans) = dp.iter().max() { println!("{}", ans); }
    else { panic!(":("); }
}

fn chmax<T>(y:T,x:&mut T) -> bool where T : std::cmp::PartialOrd { if *x < y { *x = y; true } else { false } }
fn chmin<T>(x:&mut T, y:T) -> bool where T : std::cmp::PartialOrd { if *x > y { *x = y; true } else { false } }
#[allow(dead_code)] fn input<T: std::str::FromStr>() -> T { let mut s = String::new(); std::io::stdin().read_line(&mut s).ok(); s.trim().parse().ok().unwrap() } #[allow(dead_code)] fn input_t<T: std::str::FromStr, U: std::str::FromStr>() -> (T, U) { let mut s = String::new(); std::io::stdin().read_line(&mut s).ok(); let s = s.trim().split_whitespace().collect::<Vec<&str>>(); (s[0].parse().ok().unwrap(), s[1].parse().ok().unwrap()) } #[allow(dead_code)] fn input_t3<T1: std::str::FromStr, T2: std::str::FromStr, T3: std::str::FromStr>() -> (T1, T2, T3) { let mut s = String::new(); std::io::stdin().read_line(&mut s).ok(); let s = s.trim().split_whitespace().collect::<Vec<&str>>(); (s[0].parse().ok().unwrap(), s[1].parse().ok().unwrap(), s[2].parse().ok().unwrap()) } #[allow(dead_code)] fn input_t4<T1: std::str::FromStr, T2: std::str::FromStr, T3: std::str::FromStr, T4: std::str::FromStr>() -> (T1, T2, T3, T4) { let mut s = String::new(); std::io::stdin().read_line(&mut s).ok(); let s = s.trim().split_whitespace().collect::<Vec<&str>>(); (s[0].parse().ok().unwrap(), s[1].parse().ok().unwrap(), s[2].parse().ok().unwrap(), s[3].parse().ok().unwrap()) } #[allow(dead_code)] fn input_t5<T1: std::str::FromStr, T2: std::str::FromStr, T3: std::str::FromStr, T4: std::str::FromStr, T5: std::str::FromStr>() -> (T1, T2, T3, T4, T5) { let mut s = String::new(); std::io::stdin().read_line(&mut s).ok(); let s = s.trim().split_whitespace().collect::<Vec<&str>>(); (s[0].parse().ok().unwrap(), s[1].parse().ok().unwrap(), s[2].parse().ok().unwrap(), s[3].parse().ok().unwrap(), s[4].parse().ok().unwrap()) } #[allow(dead_code)] fn input_vec<T: std::str::FromStr>() -> Vec<T> { let mut s = String::new(); std::io::stdin().read_line(&mut s).ok(); s.trim().split_whitespace().map(|s| s.parse().ok().unwrap()).collect() }