Годовой баланс

#include <iostream>
#include <fstream>
#include <vector>;
#include <algorithm>
using namespace std;

void preob(vector<int>& m, string& s, int x) {

    for (int i = 0 + x; i < s.size(); i++) {
        m.push_back(s[i] - '0');
    }

}

bool comp(int& x1, int& x2) {
    return x1 > x2;
}

void reverse_preob(int& x, vector<int>& s) {

    int nul = 0;
    int temp = 1;

    for (int i = s.size() - 1; i >= 0; i--) {
        x += s[i] * temp;
        temp *= 10;
    }

}

int main() {

    std::ifstream fin("input.txt");
    std::ofstream fout("output.txt");

    string a, b;
    fin >> a >> b;

    vector<int> temp_a, temp_b;
    bool f = false;
    if (a[0] == '-') {
        int min = a[1] - '0';
        for (int i = 2; i < a.size(); i++) {
            if (a[i] - '0' < min && a[i] != '0') {
                min = a[i] - '0';
                swap(a[i], a[1]);
            }
        }
        temp_a.push_back(min);
        preob(temp_a, a, 2);
        sort(temp_a.begin() + 1, temp_a.end());
        f = true;
    }
    else {
        preob(temp_a, a, 0);
        sort(temp_a.begin(), temp_a.end(), comp);
    }
    int kb = 0;
    if (b[0] == '-') {
        preob(temp_b, b, 1);
        sort(temp_b.begin(), temp_b.end(), comp);
        reverse_preob(kb, temp_b);
        kb *= -1;
    }
    else{
        int min = b[0] - '0';
        for (int i = 1; i < b.size(); i++) {
            if (b[i] - '0' < min && b[i] - '0' != 0) {
                min = b[i] - '0';
                swap(b[i], b[0]);
            }
        }
        temp_b.push_back(min);
        preob(temp_b, b, 1);
        sort(temp_b.begin() + 1, temp_b.end());
        reverse_preob(kb, temp_b);
    }

    int ka = 0;
    reverse_preob(ka, temp_a);
    if (f) {
        ka *= -1;
    }

    fout << ka - kb << endl;
    return 0;

}