Number 0...100 to Text

#include <iostream>
#include <iomanip>
using namespace std;

int main()
{
    int n;
    cin >> n;
    int m = n;

    if (n == 0)
        cout << "zero\n";
    else if (n <= 10)
    {
        switch (n)
        {
        case 1:
            cout << "one\n"; break;
        case 2:
            cout << "two\n"; break;
        case 3:
            cout << "three\n"; break;
        case 4:
            cout << "four\n"; break;
        case 5:
            cout << "five\n"; break;
        case 6:
            cout << "six\n"; break;
        case 7:
            cout << "seven\n"; break;
        case 8:
            cout << "eight\n"; break;
        case 9:
            cout << "nine\n"; break;
        case 10:
            cout << "ten\n"; break;

        }
    }
    else if (n > 10 && n < 20)
    {
        m %= 10;
        switch (m)
        {
        case 1:
            cout << "eleven\n"; break;
        case 2:
            cout << "twelve\n"; break;
        case 3:
            cout << "thirteen\n"; break;
        case 4:
            cout << "fourteen\n"; break;
        case 5:
            cout << "fifteen\n"; break;
        case 6:
            cout << "sixteen\n"; break;
        case 7:
            cout << "seventeen\n"; break;
        case 8:
            cout << "eighteen\n"; break;
        case 9:
            cout << "nineteen\n"; break;
        }
    }
    else if (n > 19 && n < 100)
    {
        m /= 10;

        switch (m)
        {
        case 2:
            cout << "twenty"; break;
        case 3:
            cout << "thirty"; break;
        case 4:
            cout << "forty"; break;
        case 5:
            cout << "fifty"; break;
        case 6:
            cout << "sixty"; break;
        case 7:
            cout << "seventy"; break;
        case 8:
            cout << "eighty"; break;
        case 9:
            cout << "ninety"; break;
        }

        if (n / 10 != 0)
        {
            m = n;
            m %= 10;

            switch (m)
            {
            case 1:
                cout << " one\n"; break;
            case 2:
                cout << " two\n"; break;
            case 3:
                cout << " three\n"; break;
            case 4:
                cout << " four\n"; break;
            case 5:
                cout << " five\n"; break;
            case 6:
                cout << " six\n"; break;
            case 7:
                cout << " seven\n"; break;
            case 8:
                cout << " eight\n"; break;
            case 9:
                cout << " nine\n"; break;
            }
        }
    }
    else if (n == 100)
    {
        cout << "one hundred\n";
    }
    if (n < 0 || n > 100)
    {
        cout << "invalid number\n";
    }

    return 0;
}