Raj's lucky number is 101. His girl friend Rani wants to give him a string S as a birthday present to him. She went to a shop and there are variety of strings which contains only 1 and 0 ( Binary string ) in that shop. Now in order to impress Raj , she wants to buy a string with highest number of subsequence’s of 101's . She needs your help. given a string S which contains only 1's and 0's , tell her the number of subsequence’s of 101 found in that string.

Input Format:

Only line of input file contains the string S

Output Format:

Print the result

Constraints:

1<=|S|<=1000000

S[i] belongs to {0,1}