#include <iostream>
#include <random>
#include <chrono>

using string = std::string;
void ignoreTillLineEnd();
string promptfs(string);
int promptfi(string);
string guessRank(int);

int main()
{
    std::mt19937 rand {std::random_device{}()};
    std::uniform_int_distribution clamp {1, 100};
    string name {promptfs("Enter your name:")};
    std::cout << "Hello " << name << ", welcome to guess the number.\n";
    int guesses {};
    int num {clamp(rand)}, ent {};
    do {
        if (guesses++ > 0) {
            if (ent > num)
                std::cout << "You Guessed Too High!\n";
            else
                std::cout << "You Guessed Too Low!\n";
        }
        ent = promptfi("Enter your guess:");
    }
    while (num != ent);
    std::cout << "Well done " << name << ", you guessed correctly!\n";
    std::cout << "You took " << guesses << " guesses, rank " << guessRank(guesses) << " .\n";
    return 0;
}

void ignoreTillLineEnd() {
    std::cin.ignore(std::numeric_limits<std::streamsize>::max(), '\n');
}

string promptfs(string msg) {
    bool once {};
    string toret {};
    do {
        if (once) {
            std::cin.clear();
            ignoreTillLineEnd();
            std::cout << "Input Failure!\n";
        }
        std::cout << msg << "\n";
        std::cin >> toret;
        once = true;
    }
    while (std::cin.fail());
    ignoreTillLineEnd();
    return toret;
}

int promptfi(string msg) {
    bool once {};
    int toret {};
    do {
        if (once) {
            std::cin.clear();
            ignoreTillLineEnd();
            std::cout << "Input Failure!\n";
        }
        std::cout << msg << "\n";
        std::cin >> toret;
        once = true;
    }
    while (std::cin.fail());
    ignoreTillLineEnd();
    return toret;
}

string guessRank(int g) {
    switch (g) {
    case 0:
        return "U";
    case 1:
        return "A^";
    case 2:
        return "A*";
    case 3:
        return "A";
    case 4:
    case 5:
        return "B";
    case 6:
    case 7:
        return "C";
    case 8:
    case 9:
    case 10:
        return "D";
    case 11:
    case 12:
    case 13:
        return "E";
    default:
        return "F";
    }
}