[编程题]字符个数统计 noskipws + set

#include <iostream>
#include <set>

using namespace std;

int main()
{
    set<char> s;
    char c;
    cin >> noskipws;
    while (cin >> c) {
        if (c == '\n') {
            break;
        }
        if (c >= 0 && c <= 127) {
            s.insert(c);
        }
    }
    cout << s.size() << endl;
    return 0;
}