Something

#include <iostream>
using namespace std;

struct digits
{
    unsigned freq;
    char letter;
};

int main()
{
    digits digit[26];
    for (int i = 0; i < 26; i++)
    {
        digit[i].letter = ('a' + i);
        digit[i].freq = 0;
    }
    char ch = 0;
    unsigned hivalue = 0;
    int hiindex = 0;
    
    while (ch != '.')
    {
        cin.get(ch);
        for (int i = 0; i < 26; i++)
        {
            if (tolower(ch) == digit[i].letter)
                digit[i].freq++;
        }
    }
    
    for (int i = 0; i < 25; i++)
    {
        hivalue = 0;
        hiindex = 0;
        for (int i2 = i; i2 < 26; i++)
        {
            if (digit[i2].freq < hivalue)
            {
                hivalue = digit[i2].freq;
                hiindex = i2;
            }
        }
        digit[i].freq = hivalue;
        digit[i].letter = digit[hiindex].letter;
    }
    
    for (int i = 0; i < 26; i++)
    {
        cout << "     " << digit[i].letter << "      " << digit[i].freq << endl;
    }
        
}