Problem:
Score : 400 points

Problem Statement

Given a string t, we will call it unbalanced if and only if the length of t is at least 2, and more than half of the letters in t are the same. For example, both voodoo and melee are unbalanced, while neither noon nor a is.

You are given a string s consisting of lowercase letters. Determine if there exists a (contiguous) substring of s that is unbalanced. If the answer is positive, show a position where such a substring occurs in s.

Constraints

2 ≦ |s| ≦ 10^5

s consists of lowercase letters.

Partial Score

200 points will be awarded for passing the test set satisfying 2 ≦ N ≦ 100.

Input

The input is given from Standard Input in the following format:

s

Output

If there exists no unbalanced substring of s, print -1 -1.

If there exists an unbalanced substring of s, let one such substring be s_a s_{a+1} ... s_{b} (1 ≦ a < b ≦ |s|), and print a b. If there exists more than one such substring, any of them will be accepted.

Sample Input 1

needed

Sample Output 1

2 5

The string s_2 s_3 s_4 s_5 = eede is unbalanced. There are also other unbalanced substrings. For example, the output 2 6 will also be accepted.

Sample Input 2

atcoder

Sample Output 2

-1 -1

The string atcoder contains no unbalanced substring.

Solution in C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <stdio.h>
#include <stdlib.h>

#define MAX_LEN_S (100000)

int ans_a, ans_b;
int find_unbalanced(char *s, int b, int e) {
  int cntl[26] = {}, cntr[26] = {};
  int m = (b + e) / 2;
  if (e - b < 2)  // must be longer than 2
    return 0;
  // search for unbalanced including s[m - 1] and s[m]
  // reach to the right
  cntl[s[m] - 'a']++;
  for (int i = m - 1; i >= 0; i--) {
    int max_cnt = 0;
    cntl[s[i] - 'a']++;
    for (int j = 0; j < 26; j++) {
      if (cntl[j] > max_cnt) {
        max_cnt = cntl[j];
        if (2 * max_cnt > m - i + 1) {
          ans_a = i; ans_b = m;
          return 1;
        }
      }
    }
  }
  // reach to the left
  cntr[s[m - 1] - 'a']++;
  for (int i = m; i < e; i++) {
    int max_cnt = 0;
    cntr[s[i] - 'a']++;
    for (int j = 0; j < 26; j++) {
      if (cntr[j] > max_cnt) {
        max_cnt = cntr[j];
        if (2 * max_cnt > i - m + 2) {
          ans_a = m - 1; ans_b = i;
          return 1;
        }
      }
    }    
  }
  return find_unbalanced(s, b, m) || find_unbalanced(s, m, e);
}

int main(int argc, char *argv[]) {
  char s[MAX_LEN_S + 1], len = 0, c;
  while ((c = fgetc(stdin)) != '\n')
    s[len++] = c;
  s[len] = '\0';
  if (find_unbalanced(s, 0, len))
    printf("%d %d\n", ans_a, ans_b);
  else
    printf("-1 -1\n");
  
  return 0;
}