#include <bits/stdc++.h>
using namespace std;
class Solution {
 public:
  void solve(std::istream& in, std::ostream& out) {
    string s;
    in >> s;
    for (int i = 1; i <= (int)s.size() - 2; i++) {
      if (s[i] == '@') {
        if (isalpha(s[i - 1]) && isalpha(s[i + 1]) &&
            (i - 2 >= 0 ? isalpha(s[i - 2]) : 1) &&
            (i + 2 < (int)s.size() ? isalpha(s[i + 2]) : 1))
          continue;
        else {
          out << "No solution" << '\n';
          return;
        }
      }
    }
    int pos = -1;
    for (int i = 0; i <= (int)s.size() - 1; i++)
      if (s[i] == '@') pos = i;
    if (s[0] == '@' || s[(int)s.size() - 1] == '@' || pos == -1)
      out << "No solution" << '\n';
    else {
      int ind = 0;
      while (ind < (int)s.size()) {
        while (ind < (int)s.size() && s[ind] != '@') {
          out << s[ind];
          ind++;
        }
        if (ind != (int)s.size()) {
          out << '@';
          ind++;
          if (ind - 1 == pos) {
            while (ind < (int)s.size()) {
              out << s[ind];
              ind++;
            }
            return;
          }
        }
        out << s[ind];
        ind++;
        if (ind != (int)s.size()) out << ',';
      }
    }
  }
};
void solve(std::istream& in, std::ostream& out) {
  out << fixed << std::setprecision(6);
  Solution solution;
  solution.solve(in, out);
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  istream& in = cin;
  ostream& out = cout;
  solve(in, out);
  return 0;
}
