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