A13612 | Strange Operation

Koa the Koala has a binary string $s$ of length $n$ . Koa can perform no more than $n-1$ (possibly zero) operations of the following form:

In one operation Koa selects positions $i$ and $i+1$ for some $i$ with $1 \le i < |s|$ and sets $s_i$ to $max(s_i, s_{i+1})$ . Then Koa deletes position $i+1$ from $s$ (after the removal, the remaining parts are concatenated).

Note that after every operation the length of $s$ decreases by $1$ .

How many different binary strings can Koa obtain by doing no more than $n-1$ (possibly zero) operations modulo $10^9+7$ ( $1000000007$ )?

The only line of input contains binary string $s$ ( $1 \le |s| \le 10^6$ ). For all $i$ ( $1 \le i \le |s|$ ) $s_i = 0$ or $s_i = 1$ .

On a single line print the answer to the problem modulo $10^9+7$ ( $1000000007$ ).