#include <bits/stdc++.h>
using namespace std;
int main() {
  string s;
  cin >> s;
  int l = s.length();
  bool b = 1;
  if (s[0] == '@' || s[l - 1] == '@') b = 0;
  size_t p, t = s.find('@');
  if (t == string::npos) b = 0;
  while (t != string::npos && b) {
    p = t;
    t = s.find('@', p + 1);
    if (t - p <= 2) b = 0;
    if (t != string::npos) {
      s.insert(t - 1, ",");
      p++;
      t++;
    }
  }
  cout << ((b) ? s : "No solution");
  return 0;
}
