The bear has a string *s* = *s*<sub class="lower-index">1</sub>*s*<sub class="lower-index">2</sub>... *s*<sub class="lower-index">|*s*|</sub> (record |*s*| is the string's length), consisting of lowercase English letters. The bear wants to count the number of such pairs of indices *i*, *j* (1 ≤ *i* ≤ *j* ≤ |*s*|), that string *x*(*i*, *j*) = *s*<sub class="lower-index">*i*</sub>*s*<sub class="lower-index">*i* + 1</sub>... *s*<sub class="lower-index">*j*</sub> contains at least one string "bear" as a substring.

String *x*(*i*, *j*) contains string "bear", if there is such index *k* (*i* ≤ *k* ≤ *j* - 3), that *s*<sub class="lower-index">*k*</sub> = *b*, *s*<sub class="lower-index">*k* + 1</sub> = *e*, *s*<sub class="lower-index">*k* + 2</sub> = *a*, *s*<sub class="lower-index">*k* + 3</sub> = *r*.

Help the bear cope with the given problem.
The first line contains a non-empty string *s* (1 ≤ |*s*| ≤ 5000). It is guaranteed that the string only consists of lowercase English letters.
import sys
import math


def main():
    read = sys.stdin.readline
    word: str = read().strip()
    prev = None
    total = 0
    for i, c in enumerate(word):
        if i + 3 >= len(word):
            break
        if word[i] == 'b' and word[i + 1] == 'e' and word[i + 2] == 'a' and word[i + 3] == 'r':
            prev_val = (prev if prev else 0) + 1
            # Count all string starting from the left
            l = i + 1
            r = i + 3 + 1
            left = l - 1 - (prev_val) + 1
            right = len(word) - (r + 1) + 1
            if l == 1:
                total += 1 + right
            elif r == len(word):
                total += 1 + left
            else:
                total += left * (right + 1)
                total += 1 + right
            prev = l
    print(total)


if __name__ == '__main__':
    main()
