#include <bits/stdc++.h>
using namespace std;
vector<int> a;
int main() {
  string s;
  cin >> s;
  for (int i = 0; i < s.length(); i++) {
    if (s[i] == '@') a.push_back(i);
    if (a.size() >= 2 && a[a.size() - 1] - a[a.size() - 2] <= 2) {
      cout << "No solution" << endl;
      return 0;
    }
  }
  if (s[0] == '@' || s[s.length() - 1] == '@' || a.size() == 0) {
    cout << "No solution" << endl;
    return 0;
  }
  int x = 0, y = 0;
  while (x != s.length()) {
    string t;
    for (int i = x; i <= a[y] + 1; i++) t += s[i];
    y++;
    x = a[y - 1] + 2;
    cout << t;
    if (y == a.size()) {
      for (int i = x; i < s.length(); i++) cout << s[i];
      break;
    }
    if (x == s.length()) break;
    cout << ",";
  }
  cout << endl;
  return 0;
}
