const INF: usize = 1usize << 60;

fn main() {
    let mut temp = String::new();
    std::io::stdin().read_line(&mut temp).ok();
    let temp: Vec<usize> = temp.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
    let gx = temp[0];
    let gy = temp[1];
    let n = temp[2];
    let f = temp[3];
    let crystals = (0..n).map(|_| {
            let mut temp = String::new();
            std::io::stdin().read_line(&mut temp).ok();
            let temp: Vec<usize> = temp.trim().split_whitespace().map(|s| s.parse().unwrap()).collect();
            let x = temp[0];
            let y = temp[1];
            let c = temp[2];
            (x, y, c)
        })
        .collect::<Vec<_>>();

    let mut grid = vec![vec![vec![INF; gy+1]; gx+1]; 2];
    grid[0][0][0] = 0;
    for idx in 0..n {
        let (ax, ay, c) = crystals[idx];
        for used in 0..2 {
            for i in 0..=gx {
                for j in 0..=gy {
                    if i+1 <= gx {
                        grid[used][i+1][j] = grid[used][i+1][j].min(grid[used][i][j] + f);
                    }
                    if j+1 <= gy {
                        grid[used][i][j+1] = grid[used][i][j+1].min(grid[used][i][j] + f);
                    }
                    if used == 0 && i+ax <= gx && j+ay <= gy {
                        grid[1][i+ax][j+ay] = grid[1][i+ax][j+ay].min(grid[used][i][j] + c);
                    }
                }
            }
        }
        for i in 0..=gx {
            for j in 0..=gy {
                grid[0][i][j] = grid[0][i][j].min(grid[1][i][j]);
            }
        }
    }
    println!("{}", grid[0][gx][gy].min(grid[1][gx][gy]));
}