import java.io.*;
import java.util.Locale;
import java.util.StringTokenizer;

public class TaskA {
    private final InputReader reader;
    private final OutputWriter writer;

    public TaskA(InputReader reader, OutputWriter writer) {
        this.reader = reader;
        this.writer = writer;
    }

    public static void main(String[] args) {
        InputReader reader = new InputReader(System.in);
        OutputWriter writer = new OutputWriter(System.out);
        new TaskA(reader, writer).run();
        writer.writer.flush();
    }

    public void run() {
        long A = reader.nextInt();
        long B = reader.nextInt();
        int n = reader.nextInt();
        for (int i = 0; i < n; i++) {
            int l = reader.nextInt();
            int t = reader.nextInt();
            int m = reader.nextInt();
            long a = 0, b = 2 * Math.max(t, m) + 1;
            while (b - a > 1) {
                long q = (a + b) / 2;
                if (A + (l + q - 2) * 1l * B <= t && (A + (l - 1) * 1l * B) * 1l * q + B * 1l * q * (q - 1) / 2 <= m * 1l * t)
                    a = q;
                else
                    b = q;
            }
            writer.printf("%d\n", (a == 0) ? -1 : l + a - 1);
        }
    }


    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            tokenizer = null;
        }

        public String next() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(reader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer.nextToken();
        }

        public int nextInt() {
            return Integer.parseInt(next());
        }

        public double nextDouble() {
            return Double.parseDouble(next());
        }

        public long nextLong() {
            return Long.parseLong(next());
        }
    }

    static class OutputWriter {
        public PrintWriter writer;

        OutputWriter(OutputStream stream) {
            writer = new PrintWriter(stream);
        }

        public void printf(String format, Object... args) {
            writer.print(String.format(Locale.ENGLISH, format, args));
        }
    }
}