ZOJ Problem Set - 3171
Given a string of characters, you may find that the word "seven" is hidden inside. For example, in the string "sesveven", five 7's are hidden:
sesveven sesveven sesveven sesveven sesvevenYour task is to count the number of different 7's.
Upper-case letters are considered as the same as the lower-case letters.
Each case gives the string in a line. The length of the string is not more than 10000.
For each test cases, output in a line the number of different 7's hidden inside the string. The result will be less than 2^63.
Author: CHEN, Yue
Source: ZOJ 7th Anniversary Contest