A9314 | Bear and Strings

The bear has a string $s=s_{1}s_{2}...\ s_{|s|}$ (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 $x(i,j)=s_{i}s_{i+1}...\ s_{j}$ 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 $s_{k}=b$ , $s_{k+1}=e$ , $s_{k+2}=a$ , $s_{k+3}=r$ .

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.

Print a single number — the answer to the problem.