import java.io.IOException;
import java.io.InputStream;
import java.util.NoSuchElementException;
import java.util.PriorityQueue;


public class Main {
  public static void main(String[] args) {
    FastScanner sc = new FastScanner();
    int gx = sc.nextInt();
    int gy = sc.nextInt();
    int N = sc.nextInt();
    int F = sc.nextInt();
    
    int[][] w = new int[N + 2][3];
    for (int i = 0; i < N; i ++) {
      w[i][0] = sc.nextInt();
      w[i][1] = sc.nextInt();
      w[i][2] = sc.nextInt();
    }
    w[N] = new int[]{1, 0, F};
    w[N + 1] = new int[]{0, 1, F};
    
    System.out.println(dijkstra(gx, gy, w));
    
  }

  public static long dijkstra(int gx, int gy, int[][] w) {

    long[][] distance = new long[gx + 1][gy + 1];
    boolean[][] visited = new boolean[gx + 1][gy + 1];

    for (int i = 0; i <= gx; i++) {
      for (int j = 0; j <= gy; j++) {
        distance[i][j] = Integer.MAX_VALUE / 3;
      }
    }

    PriorityQueue<int[]> queue = new PriorityQueue<>((a, b) -> {
      if (distance[a[0]][a[1]] == distance[b[0]][b[1]]) {
        return a[0] * 1000 + a[1] - b[0] * 1000 + b[1];
      } else {
        return Long.compare(distance[a[0]][a[1]], distance[b[0]][b[1]]);
      }
    });
    distance[0][0] = 0;
    queue.add(new int[]{0, 0});

    
    while (queue.size() > 0) {
        int[] elem = queue.poll();
        int x = elem[0];
        int y = elem[1];
        long len = distance[x][y];
        visited[x][y] = true;

        for (int[] v : w) {
          int nx = x + v[0];
          int ny = y + v[1];
            if (nx <= gx && ny <= gy && !visited[nx][ny]) {
                long newCost = len + v[2];
                if (newCost < distance[nx][ny]) {
                    queue.add(new int[]{nx, ny});
                    distance[nx][ny] = newCost;
                }
            }
        }
    }
    return distance[gx][gy];
  }
}


class FastScanner {
	public static String debug = null;

	private final InputStream in = System.in;
	private int ptr = 0;
	private int buflen = 0;
	private byte[] buffer = new byte[1024];
	private boolean eos = false;

	private boolean hasNextByte() {
		if (ptr < buflen) {
			return true;
		} else {
			ptr = 0;
			try {
				if (debug != null) {
					buflen = debug.length();
					buffer = debug.getBytes();
					debug = "";
					eos = true;
				} else {
					buflen = in.read(buffer);
				}
			} catch (IOException e) {
				e.printStackTrace();
			}
			if (buflen < 0) {
				eos = true;
				return false;
			} else if (buflen == 0) {
				return false;
			}
		}
		return true;
	}

	private int readByte() {
		if (hasNextByte())
			return buffer[ptr++];
		else
			return -1;
	}

	private static boolean isPrintableChar(int c) {
		return 33 <= c && c <= 126;
	}

	private void skipUnprintable() {
		while (hasNextByte() && !isPrintableChar(buffer[ptr]))
			ptr++;
	}

	public boolean isEOS() {
		return this.eos;
	}

	public boolean hasNext() {
		skipUnprintable();
		return hasNextByte();
	}

	public String next() {
		if (!hasNext())
			throw new NoSuchElementException();
		StringBuilder sb = new StringBuilder();
		int b = readByte();
		while (isPrintableChar(b)) {
			sb.appendCodePoint(b);
			b = readByte();
		}
		return sb.toString();
	}

	public long nextLong() {
		if (!hasNext())
			throw new NoSuchElementException();
		long n = 0;
		boolean minus = false;
		int b = readByte();
		if (b == '-') {
			minus = true;
			b = readByte();
		}
		if (b < '0' || '9' < b) {
			throw new NumberFormatException();
		}
		while (true) {
			if ('0' <= b && b <= '9') {
				n *= 10;
				n += b - '0';
			} else if (b == -1 || !isPrintableChar(b)) {
				return minus ? -n : n;
			} else {
				throw new NumberFormatException();
			}
			b = readByte();
		}
	}

	public int nextInt() {
		return (int) nextLong();
	}

	public long[] nextLongList(int n) {
		return nextLongTable(1, n)[0];
	}

	public int[] nextIntList(int n) {
		return nextIntTable(1, n)[0];
	}

	public long[][] nextLongTable(int n, int m) {
		long[][] ret = new long[n][m];
		for (int i = 0; i < n; i ++) {
			for (int j = 0; j < m; j ++) {
				ret[i][j] = nextLong();
			}
		}
		return ret;
	}

	public int[][] nextIntTable(int n, int m) {
		int[][] ret = new int[n][m];
		for (int i = 0; i < n; i ++) {
			for (int j = 0; j < m; j ++) {
				ret[i][j] = nextInt();
			}
		}
		return ret;
	}
}