#include <bits/stdc++.h>
using namespace std;
int main() {
  string s, k = "";
  cin >> s;
  vector<long long> v;
  long long n = -1;
  for (int i = 0; i < s.size(); i++) {
    if (s[i] == '@') {
      v.push_back(i);
      if (v.size() > 1 && i - v[n] <= 2) {
        cout << "No solution";
        return 0;
      }
      n++;
    }
  }
  int c = 0;
  if (v.size() == 0) {
    cout << "No solution";
    return 0;
  }
  if ((s[0] == '@' || s[s.size() - 1] == '@')) {
    cout << "No solution";
    return 0;
  }
  if (v.size() == 1) {
    cout << s << "\n";
    return 0;
  }
  for (int i = 0; i < s.size(); i++) {
    if (v[c] == i && c < (v.size() - 1)) {
      k.push_back(s[i]);
      k.push_back(s[i + 1]);
      k.push_back(',');
      c++;
      i++;
    } else {
      k += s[i];
    }
  }
  cout << k << "\n";
  return 0;
}
