CPP cout question.

I'd like to ask you a very basic question

I was not used to using the cout command, so I was curious about it after trying many things.

If you look at the code below, for convenience of explanation, we put the constant in "" for cases 1 to 6 and marked only the constant for cases 7 to 12.

When I tried the output in two comparative ways, both worked fine.

The question I want to ask here is whether it is okay to use without quotation marks when outputting constants from cout!

using namespace::std;

int main() { int mon;

cin >> mon;

switch (mon){
case 1 : cout << "31"; break;
case 2 : cout << "28"; break;
case 3 : cout << "31"; break;
case 4 : cout << "30"; break;
case 5 : cout << "31"; break;
case 6 : cout << "30"; break;
case 7 : cout << 31; break;
case 8 : cout << 31; break;
case 9 : cout << 30; break;
case 10 : cout << 31; break;
case 11 : cout << 30; break;
case 12 : cout << 31; break;
}

return 0;

}