#include <bits/stdc++.h>
using namespace std;
vector<int> v;
int main() {
  string s1;
  cin >> s1;
  int count = 0;
  for (int i = 0; i < s1.size(); i++)
    if (s1[i] == '@') count++;
  if (count == 0) {
    cout << "No solution";
    return 0;
  }
  for (int i = 0; i < s1.size(); i++)
    if (s1[i] == '@') v.push_back(i);
  if (v[0] == 0 || v[v.size() - 1] == s1.size() - 1) {
    cout << "No solution";
    return 0;
  }
  for (int i = 1; i < v.size(); i++)
    if (v[i] - v[i - 1] <= 2) {
      cout << "No solution";
      return 0;
    }
  for (int i = 0; i < s1.size(); i++) {
    if (s1[i - 1] == '@' && i - 1 != v[v.size() - 1]) {
      cout << s1[i] << ",";
    } else
      cout << s1[i];
  }
  return 0;
}
