#include <bits/stdc++.h>
using namespace std;
int main() {
  string s;
  cin >> s;
  if (s[0] == '@' || s[s.size() - 1] == '@') {
    cout << "No solution" << endl;
    return 0;
  }
  vector<int> a;
  for (int i = 0; i < s.size(); i++) {
    if (s[i] == '@') {
      a.push_back(i);
    }
  }
  for (int i = 1; i < a.size(); i++) {
    if (a[i] - a[i - 1] < 3) {
      cout << "No solution" << endl;
      return 0;
    }
  }
  if (a.empty()) {
    cout << "No solution" << endl;
    return 0;
  }
  int counter = a.size() - 1;
  for (int i = 0; i < s.size(); i++) {
    cout << s[i];
    if (s[i] == '@' && counter > 0) {
      cout << s[++i] << ',';
      counter--;
    }
  }
  return 0;
}
