Как выйти из нескольких вложенных циклов?

По задумке после выполнения математической операции код должен повторяться и заново выводить ввод операции.Но на деле получается выйти только из одного цикла,если писать Break.А завершать программу полностью должен case 'br',но получилось так,что он бесполезен

#include <iostream>
#include <math.h>
using namespace std;
float sum(float a, float b) {
    return(a + b);
}
float sum(float a, float b,float c) {
    return(a + b + c);
}
float min(float a, float b) {
    return(a - b);
}
float min(float a, float b, float c) {
    return(a - b - c);
}
float mult(float a, float b) {
    return(a * b);
}
float mult(float a, float b,float c) {
    return(a * b * c);
}
float div(float a, float b) {
    return(a / b);
}
float div(float a, float b, float c) {
    return(a / b / c);
}
float square(float a) {
    return(a * a);
}
float cube(float a) {
    return(a * a * a);
}
float root(float a, float b) {
    return(pow(a, 1 / b));
}
float degree(float a, float b) {
    return(pow(a, b));
}
void main() {
    char command;
    cout << "commands:" << "\n" << "+" << "\n" << "-" << "\n" << "*" << "\n" << "/" << "\n" << "*2 - square" << "\n" << "*3 - cube" << "\n" << "// - root" << "\n" << "** - degree" <<"\n"<<"br - break"<< endl;
    cin >> command;
    for (int num;;) {
        float a, b, c;
        switch (command)
        {
        case '+':

            cout << "enter the number of numbers (2 or 3)" << endl;
            cin >> num;

            if (num == 2) {

                float a, b;
                cout << "enter 2 numbers" << endl;
                cin >> a >> b;
                cout << "result:" << sum(a, b) << endl;
                return;
            }
            else if (num == 3) {

                float a, b, c;
                cout << "enter 3 numbers" << endl;
                cin >> a >> b >> c;
                cout << "result:" << "\n" << sum(a, b, c) << endl;
                return;
            }
            else

                cout << "error" << endl;
                break;

        case '-':

            cout << "enter the number of numbers (2 or 3)" << endl;
            cin >> num;

            if (num == 2) {

                float a, b;
                cout << "enter 2 numbers" << endl;
                cin >> a >> b;
                cout << "result:" << "\n" << min(a, b) << endl;
                return;
            }
            else if (num == 3) {

                float a, b, c;
                cout << "enter 3 numbers" << endl;
                cin >> a >> b >> c;
                cout << "result:" <<"\n" << min(a, b, c) << endl;
                return;
            }
            else

                cout << "enter another value" << endl;
            break;

        case '*':

            cout << "enter the number of numbers (2 or 3)" << endl;
            cin >> num;

            if (num == 2) {

                cout << "enter 2 numbers" << endl;
                cin >> a >> b;
                cout << "result:" << "\n" << mult(a, b) << endl;
                return;
            }
            else if (num == 3) {

                cout << "enter 3 numbers" << endl;
                cin >> a >> b >> c;
                cout << "result:" << "\n" << mult(a, b, c) << endl;
                return;
            }
            else

                cout << "enter another value" << endl;
            break;

        case '/':

            cout << "enter the number of numbers (2 or 3)" << endl;
            cin >> num;

            if (num == 2) {

                cout << "enter 2 numbers" << endl;
                cin >> a >> b;
                cout << "result:" << "\n" << div(a, b) << endl;
                return;
            }
            else if (num == 3) {

                cout << "enter 3 numbers" << endl;
                cin >> a >> b >> c;
                cout << "result:" << "\n" << div(a, b, c) << endl;
                return;
            }
            else

                cout << "enter another value" << endl;
            break;

        case '*2': 

            cout << "enter the number" << endl;
            cin >> a;
            cout << "result:" << "\n" << square(a) << endl;
            return;

        case '*3':

            cout << "enter the number" << endl;
            cin >> a;
            cout << "result:" << "\n" << cube(a) << endl;
            return;

        case '//':

            cout << "enter number and degree" << endl;
            cin >> a >> b;
            cout << "result:" << "\n" << root(a, b) << endl;
            return;

        case '**':

            cout << "enter number and degree" << endl;
            cin >> a >> b;
            cout << "result:" << "\n" << degree(a, b) << endl;
            return;

        case 'br':
            cout << "end" << endl;
            return ;
        default:
            cout << "error" << endl;
            return;
        }
    }
}