#include <bits/stdc++.h>
using namespace std;
const int mod = 1e9 + 7;
const int inf = 2e9 + 5;
const int N = 101;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  cout.tie(nullptr);
  string s;
  cin >> s;
  int n = s.length();
  vector<int> pos;
  for (int i = 0; i < n; i++) {
    if (s[i] == '@') pos.push_back(i);
  }
  if (pos.empty() or pos.front() == 0 or pos.back() == n - 1) {
    cout << "No solution\n";
    return 0;
  }
  for (int i = 1; i < pos.size(); i++) {
    if (pos[i] - pos[i - 1] <= 2) {
      cout << "No solution\n";
      return 0;
    }
  }
  string temp;
  bool flag = false;
  for (int i = 0; i < n; i++) {
    if (pos.back() == i) {
      cout << temp;
      for (int j = i; j < n; j++) cout << s[j];
      return 0;
    }
    if (s[i] == '@') flag = true;
    temp += s[i];
    if (s[i] != '@' and flag) {
      cout << temp << ",";
      temp.clear();
      flag = false;
    }
  }
  return 0;
}
