Удалить из множества А минимальный элемент множества В

#include <iostream>
#include <string>
#include <conio.h>
using namespace std;
 
int main()
{
    string s1,s2;
    cout <<"S1 = ";
    getline (cin,s1);
    cout <<"S2 = ";
    getline (cin,s2);
    for (int i=0; i<s2.size(); i++)
    {
        while (s1.find(s2[i])!=-1)
            s1.erase(s1.find(s2[i]),1);
    }
    cout <<"------------------------\n" <<s1 <<endl <<s2 <<endl;
    _getch();
    return 0;
}

#include <algorithm>
#include <iterator>
#include <iostream>
#include <set>
 
int main()
{
    std::set <int> firstSet = { 1, 2, 3, 4, 5, 6 };
    std::cout << "First set: { ";
    std::copy(firstSet.begin(), firstSet.end(), std::ostream_iterator <int> (std::cout, " "));
    std::cout << "} " << std::endl;
 
    std::set <int> secondSet = { 6, 7, 8, 9, 10 };
    std::cout << "Second set: { ";
    std::copy(secondSet.begin(), secondSet.end(), std::ostream_iterator <int> (std::cout, " "));
    std::cout << "} " << std::endl;
 
    int minimalOfSecondSet(*std::min_element(secondSet.begin(), secondSet.end()));
    std::cout << "Minimal of the second set: " << minimalOfSecondSet << std::endl;
 
    firstSet.erase(minimalOfSecondSet);
    std::cout << "First set: { ";
    std::copy(firstSet.begin(), firstSet.end(), std::ostream_iterator <int>(std::cout, " "));
    std::cout << "} " << std::endl;
 
    std::system("pause");
    return 0;
}

#include <algorithm>
#include <iostream>
#include <iterator>
#include <set>
 
int main()
{
    size_t firstSetSize;
    std::cout << "Size of the first set: ";
    std::cin >> firstSetSize;
 
    std::set <int> firstSet;
    std::cout << "Input " << firstSetSize << " unique elements: " << std::endl;
    for (size_t i = 0; i < firstSetSize; i++) {
        int currentSetElement;
        std::cout << (i + 1) << ") ";
        std::cin >> currentSetElement;
        if (std::count(firstSet.begin(), firstSet.end(), currentSetElement)) {
            std::cout << "This element in not unique! Try again!" << std::endl;
            i--;
        }
        else {
            firstSet.insert(currentSetElement);
        }
    }
    std::system("cls");
 
    size_t secondSetSize;
    std::cout << "Size of the second set: ";
    std::cin >> secondSetSize;
 
    std::set <int> secondSet;
    std::cout << "Input " << secondSetSize << " unique elements: " << std::endl;
    for (size_t i = 0; i < secondSetSize; i++) {
        int currentSetElement;
        std::cout << (i + 1) << ") ";
        std::cin >> currentSetElement;
        if (std::count(secondSet.begin(), secondSet.end(), currentSetElement)) {
            std::cout << "This element in not unique! Try again!" << std::endl;
            i--;
        } else {
            secondSet.insert(currentSetElement);
        }
    }
    std::system("cls");
 
    std::cout << "First set: { ";
    std::copy(firstSet.begin(), firstSet.end(), std::ostream_iterator <int>(std::cout, " "));
    std::cout << "} " << std::endl;
 
    std::cout << "Second set: { ";
    std::copy(secondSet.begin(), secondSet.end(), std::ostream_iterator <int>(std::cout, " "));
    std::cout << "} " << std::endl;
 
    int minimalOfSecondSet(*std::min_element(secondSet.begin(), secondSet.end()));
    std::cout << "Minimal of the second set: " << minimalOfSecondSet << std::endl;
 
    firstSet.erase(minimalOfSecondSet);
    std::cout << "First set: { ";
    std::copy(firstSet.begin(), firstSet.end(), std::ostream_iterator <int>(std::cout, " "));
    std::cout << "} " << std::endl;
 
    std::system("pause");
    return 0;
}