source_code: import java.util.*;
  
  public class TaskF {
      public static void main(String[] args) {
          Scanner in = new Scanner(System.in);
  
          int n = in.nextInt();
          int[] a = new int[n + 1];
          for (int i = 1; i <= n; i++) {
              a[i] = in.nextInt();
          }
  
          int[] prefixSum = new int[n + 1];
          prefixSum[0] = 0;
          for (int i = 1; i <= n; i++) {
              prefixSum[i] = prefixSum[i - 1] + a[i];
          }
  
          Map<Integer, List<Segment>> sumToSegments = new HashMap<>();
          for (int i = 1; i <= n; i++) {
              for (int j = i; j <= n; j++) {
                  int sum = prefixSum[j] - prefixSum[i - 1];
                  sumToSegments
                          .computeIfAbsent(sum, $ -> new ArrayList<>())
                          .add(Segment.make(i, j));
              }
          }
  
          List<Segment> bestSegments = null;
          for (int sum : sumToSegments.keySet()) {
              List<Segment> segments = sumToSegments.get(sum);
              int size = segments.size();
  
              int[] f = new int[size];
              int[] next = new int[size];
              boolean[] take = new boolean[size];
  
              f[size - 1] = 1;
              next[size - 1] = -1;
              take[size - 1] = true;
              int bestStartIndex = size - 1;
  
              for (int i = size - 2; i >= 0; i--) {
                  int nextIndex;
  
                  if (segments.get(i).q >= segments.get(size - 1).p) {
                      nextIndex = -1;
                  } else {
                      int L = i + 1;
                      int R = size - 1;
                      while (L < R) {
                          int M = (L + R) / 2;
                          if (segments.get(i).q >= segments.get(M).p) { /* intersection */
                              L = M + 1;
                          } else {
                              R = M;
                          }
                      }
                      nextIndex = L;
                  }
  
                  f[i] = 1 + ((nextIndex == -1) ? 0 : f[nextIndex]);
                  next[i] = nextIndex;
                  take[i] = true;
  
                  if (f[i + 1] > f[i]) {
                      take[i] = false;
                      f[i] = f[i + 1];
                      next[i] = i + 1;
                  }
  
                  if (bestStartIndex == -1 || f[i] > f[bestStartIndex]) {
                      bestStartIndex = i;
                  }
              }
  
              // recover segment set
              List<Segment> maxForSum = new ArrayList<>();
              int index = bestStartIndex;
              do {
                  if (take[index]) {
                      maxForSum.add(segments.get(index));
                  }
                  index = next[index];
              } while (index != -1);
  
              if (bestSegments == null || maxForSum.size() > bestSegments.size()) {
                  bestSegments = maxForSum;
              }
          }
  
          System.out.println(bestSegments.size());
          for (Segment segment : bestSegments) {
              System.out.printf("%s %s%n", segment.p, segment.q);
          }
  
          in.close();
      }
  
      private static class Segment {
          public final int p;
          public final int q;
  
          private Segment(int p, int q) {
              this.p = p;
              this.q = q;
          }
  
          public static Segment make(int p, int q) {
              return new Segment(p, q);
          }
      }
  }
  