#include <bits/stdc++.h>
using namespace std;
int main() {
  string s;
  cin >> s;
  int a[1000], kol = 1;
  a[0] = -10;
  for (int i = 0; i < s.size(); ++i)
    if (s[i] == '@')
      if (i - a[kol - 1] < 3)
        cout << "No solution", exit(0);
      else
        a[kol++] = i;
  for (int i = kol - 2; i > 0; --i) s.insert(a[i] + 2, ",");
  if (kol == 1 || s[0] == '@' || s[s.size() - 1] == '@')
    cout << "No solution";
  else
    cout << s;
  return 0;
}
