#include <iostream>

int main()
{
    std::cout<<"Welcome to Stats Array!\n"
    <<"These are your choices:\n"
    <<"N- Numbers\n"
    <<"S- Sum of all\n"
    <<"A- Average of all\n"
    <<"B- Biggest of all\n"
    <<"F- Most Frequent of all\n"
    <<"H- How many numbers\n"
    <<"M- Median of all\n"
    <<"Q- Quit\n";

    bool running = true;
    int frequency[100] = {0};

    // run until user specifies to stop
    while(running) {
        char choice;
        int numInput;
        std::cin>>choice;
        switch (choice) {
            // add input to frequency
            case 'N': {
                std::cin>>numInput;
                frequency[numInput] += 1;
                std::cout<<"OK"<<std::endl;
                break;
            }
            // sum of all numbers
            case 'S': {
                int sum = 0;
                for (int i = 0; i < 100; i++) {
                    if (frequency[i] > 0) {
                        sum += i * frequency[i];
                    }
                }
                std::cout<<sum<<std::endl;
                break;
            }
            // average of all numbers
            case 'A': {
                int sum = 0;
                int num = 0;
                for (int i = 0; i < 100; i++) {
                    if (frequency[i] > 0) {
                        num += frequency[i];
                        sum += i * frequency[i];
                    }
                }
                if(num == 0) {
                    std::cout<<"ERROR"<<std::endl;
                    break;
                }
                double avg = sum/(double)num;
                std::cout<<avg<<std::endl;
                break;
            }
            // biggest of all numbers
            case 'B': {
                int biggest = 0;
                for (int i = 0; i < 100; i++) {
                    if (frequency[i] > 0) {
                        biggest = i;
                    }
                }
                if (biggest == 0) {
                    std::cout<<"ERROR"<<std::endl;
                    break;
                }
                std::cout<<biggest<<std::endl;
                break;
            }
            // most frequent of all numbers
            case 'F': {
                int num = 0;
                for (int i = 0; i < 100; i++) {
                    if (frequency[i] > frequency[num]) {
                        num = i;
                    }
                }
                if (frequency[num] == 0) {
                    std::cout<<"ERROR"<<std::endl;
                    break;
                }
                std::cout<<num<<std::endl;
                break;
            }
            // count of how many numbers
            case 'H': {
                int howMany = 0;
                for (int i = 0; i < 100; i++) {
                    if (frequency[i] > 0) {
                        howMany += frequency[i];
                    }
                }
                std::cout<<howMany<<std::endl;
                break;
            }
            // median of all numbers
            case 'M': {
                int howMany = 0;
                for (int i = 0; i < 100; i++) {
                    if (frequency[i] > 0) {
                        howMany += frequency[i];
                    }
                }
                if (howMany == 0) {
                    std::cout<<"ERROR"<<std::endl;
                    break;
                }
                int median = howMany / 2 + 1;
                std::cout<<median<<std::endl;
                break;
            }
            // quit the program
            case 'Q': {
                running = false;
                break;
            }
            // input error handling
            default: {
                std::cout<<"Bad input. Try capitalizing the letter."<<std::endl;
                break;
            }
        }
    }
}