source_code: import java.io.OutputStream;
  import java.io.IOException;
  import java.io.InputStream;
  import java.io.OutputStream;
  import java.io.PrintWriter;
  import java.io.BufferedWriter;
  import java.util.HashMap;
  import java.util.InputMismatchException;
  import java.io.IOException;
  import java.util.ArrayList;
  import java.io.Writer;
  import java.io.OutputStreamWriter;
  import java.io.InputStream;
  
  /**
   * Built using CHelper plug-in
   * Actual solution is at the top
   *
   * @author revanth
   */
  public class Main {
      public static void main(String[] args) {
          InputStream inputStream = System.in;
          OutputStream outputStream = System.out;
          InputReader in = new InputReader(inputStream);
          OutputWriter out = new OutputWriter(outputStream);
          F2SameSumBlocksHard solver = new F2SameSumBlocksHard();
          solver.solve(1, in, out);
          out.close();
      }
  
      static class F2SameSumBlocksHard {
          public void solve(int testNumber, InputReader in, OutputWriter out) {
              int n = in.nextInt();
              long[] a = in.nextLongArray(n);
              HashMap<Long, ArrayList<Pair>> hm = new HashMap<>();
              long sum;
              for (int j = 0; j < n; j++) {
                  sum = 0;
                  for (int i = j; i >= 0; i--) {
                      sum += a[i];
                      if (!hm.containsKey(sum))
                          hm.put(sum, new ArrayList<>());
                      hm.get(sum).add(new Pair(i + 1, j + 1));
                  }
              }
              ArrayList<Pair> al1 = new ArrayList<>();
              ArrayList<Pair> al2 = new ArrayList<>();
              int prev;
              for (ArrayList<Pair> al : hm.values()) {
                  prev = 0;
                  al1.clear();
                  for (Pair p : al) {
                      if (p.x > prev) {
                          al1.add(p);
                          prev = p.y;
                      }
                  }
                  if (al1.size() > al2.size())
                      al2 = new ArrayList<>(al1);
              }
              out.println(al2.size());
              for (Pair p : al2)
                  out.println(p.x + " " + p.y);
          }
  
      }
  
      static class InputReader {
          private InputStream stream;
          private byte[] buf = new byte[8192];
          private int curChar;
          private int snumChars;
          private InputReader.SpaceCharFilter filter;
  
          public InputReader(InputStream stream) {
              this.stream = stream;
          }
  
          public int snext() {
              if (snumChars == -1)
                  throw new InputMismatchException();
              if (curChar >= snumChars) {
                  curChar = 0;
                  try {
                      snumChars = stream.read(buf);
                  } catch (IOException e) {
                      throw new InputMismatchException();
                  }
                  if (snumChars <= 0)
                      return -1;
              }
              return buf[curChar++];
          }
  
          public int nextInt() {
              int c = snext();
              while (isSpaceChar(c))
                  c = snext();
              int sgn = 1;
              if (c == '-') {
                  sgn = -1;
                  c = snext();
              }
              int res = 0;
              do {
                  if (c < '0' || c > '9')
                      throw new InputMismatchException();
                  res *= 10;
                  res += c - '0';
                  c = snext();
              } while (!isSpaceChar(c));
              return res * sgn;
          }
  
          public long nextLong() {
              int c = snext();
              while (isSpaceChar(c))
                  c = snext();
              int sgn = 1;
              if (c == '-') {
                  sgn = -1;
                  c = snext();
              }
              long res = 0;
              do {
                  if (c < '0' || c > '9')
                      throw new InputMismatchException();
                  res *= 10;
                  res += c - '0';
                  c = snext();
              } while (!isSpaceChar(c));
              return res * sgn;
          }
  
          public long[] nextLongArray(int n) {
              long a[] = new long[n];
              for (int i = 0; i < n; i++)
                  a[i] = nextLong();
              return a;
          }
  
          public boolean isSpaceChar(int c) {
              if (filter != null)
                  return filter.isSpaceChar(c);
              return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
          }
  
          public interface SpaceCharFilter {
              public boolean isSpaceChar(int ch);
  
          }
  
      }
  
      static class Pair implements Comparable<Pair> {
          public int x;
          public int y;
  
          public Pair(int x, int y) {
              this.x = x;
              this.y = y;
          }
  
          public boolean equals(Object obj) {
              if (obj == null)
                  return false;
              if (obj == this)
                  return true;
              if (!(obj instanceof Pair))
                  return false;
              Pair o = (Pair) obj;
              return o.x == this.x && o.y == this.y;
          }
  
          public int hashCode() {
              return this.x + this.y;
          }
  
          public int compareTo(Pair p) {
              if (x == p.x)
                  return Integer.compare(y, p.y);
              return Integer.compare(x, p.x);
          }
  
      }
  
      static class OutputWriter {
          private final PrintWriter writer;
  
          public OutputWriter(OutputStream outputStream) {
              writer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(outputStream)));
          }
  
          public OutputWriter(Writer writer) {
              this.writer = new PrintWriter(writer);
          }
  
          public void print(Object... objects) {
              for (int i = 0; i < objects.length; i++) {
                  if (i != 0) {
                      writer.print(' ');
                  }
                  writer.print(objects[i]);
              }
          }
  
          public void println(Object... objects) {
              print(objects);
              writer.println();
          }
  
          public void close() {
              writer.close();
          }
  
      }
  }
  
  