#include <bits/stdc++.h>
using namespace std;
int main() {
    string a;
    cin >> a;
    int len = a.size();
    int last;
    bool flag;
    if (a[0] == '@' || a[len - 1] == '@') {
        cout << "No solution";
        return 0;
    }
    for (int i = 1; i < len - 1; i ++) {
        if ((a[i] == '@' && a[i + 1] == '@') || (a[i] == '@' && a[i + 2] == '@')) {
            cout << "No solution";
            return 0;
        }
        if (a[i] == '@') {
            flag = 1;
            last = i;
        }
    }
    if (!flag) {
        cout << "No solution";
        return 0;
    }
    for (int i = 0; i < len; i ++) {
        cout << a[i];
        if (a[i - 1] == '@' && i != len - 1 && i < last) {
            cout << ",";
        }
    }
    return 0;
}