// Жаккар

#include <iostream>
#include <regex>
#include <algorithm>


std::string stringNormalization(std::string str) {
    const std::regex regexFirst{ R"(_|[^\d\w\s])" };
    const std::regex regexSecond{ R"(\b\w{1,3}\b)" };
    const std::regex regexThird{ R"(\s{2,})" };

    str = std::regex_replace(str, regexFirst, "");
    str = std::regex_replace(str, regexSecond, "");
    str = std::regex_replace(str, regexThird, " ");

    std::transform(str.begin(), str.end(), str.begin(), ::tolower);

    str.erase(0, str.find_first_not_of(' '));

    return str;
}


double FindC(std::string first, std::string second) {
    double counter{};

    for (int i{}; i < std::min(first.length(), second.length()); ++i) {
        if (first[i] == second[i]) {
            counter += 1.0;
        }
    }

    return counter;
}


int main() {
    std::string inputFirst, inputSecond;
    std::getline(std::cin, inputFirst);
    std::getline(std::cin, inputSecond);

    inputFirst = stringNormalization(inputFirst);
    inputSecond = stringNormalization(inputSecond);

    double c = FindC(inputFirst, inputSecond);
    double result = c / (inputFirst.length() + inputSecond.length() - c);

    std::cout << result << std::endl;

    return 0;
}