include[HTML_REMOVED]
include[HTML_REMOVED]
using namespace std;
int fuc(string n) {
int s = 0;
for (int i = 0; i < n.size(); i++) {
s += n[i] - ‘0’;
}
if (s >= 0 && s <= 9) return s;
else {
string n1 = to_string(s);
return fuc(n1);
}
}
int main() {
string n;
while (cin >> n) {
if (n == “0”) break;
int x = fuc(n);
cout << x << endl;
}
return 0;
}