#include <bits/stdc++.h>
using namespace std;
bool check(string& a) {
  int first = -1;
  for (int i = 0; i < a.size(); i++) {
    if (a[i] == '@') {
      first = i;
    }
  }
  return (0 < first && first < a.size() - 1);
}
void solve() {
  string s;
  cin >> s;
  string cur;
  vector<string> ans;
  int n = s.size();
  if (n < 3 || s[0] == '@' || s[n - 1] == '@') {
    cout << "No solution" << '\n';
    return;
  }
  bool ok = false;
  for (int i = 0; i < s.size(); i++) {
    if (s[i] != '@') {
      cur += s[i];
    } else if (i + 1 < s.size()) {
      ok = true;
      cur += s[i];
      cur += s[i + 1];
      if (!check(cur)) {
        cout << "No solution" << '\n';
        return;
      }
      ans.push_back(cur);
      cur.clear();
      i++;
    }
  }
  if (!ok) {
    cout << "No solution" << '\n';
    return;
  }
  ans.back() += cur;
  int m = ans.size();
  for (int i = 0; i < m; i++) {
    cout << ans[i] << (i == m - 1 ? '\n' : ',');
    ;
  }
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  solve();
  return 0;
}
