#include <bits/stdc++.h>
using namespace std;
int main() {
  string s;
  int a[200];
  cin >> s;
  int l = s.length(), la = 0;
  ;
  for (int i = 0; i < l; i++) {
    if (s[i] == '@') {
      a[la] = i;
      la++;
    }
  }
  bool check = false;
  if (!la || !a[0] || a[la - 1] == l - 1) check = true;
  for (int i = 1; i < la; i++)
    if (a[i] - a[i - 1] <= 2) check = true;
  if (check) {
    cout << "No solution";
  } else {
    int j = 0;
    for (int i = 0; i < l; i++) {
      cout << s[i];
      if (i == a[j] + 1 && j != la - 1) {
        cout << ',';
        j++;
      }
    }
  }
  return 0;
}
