#include <bits/stdc++.h>
using namespace std;
int main() {
  string str;
  cin >> str;
  int n = str.length();
  string ans = "";
  if (str[0] == '@' || str[n - 1] == '@') ans = "No solution";
  int pre = -2;
  for (int i = 1; i < n; i++) {
    if (str[i] == '@') {
      if ((i - pre) <= 2) {
        ans = "No solution";
        break;
      } else {
        pre = i;
      }
    }
  }
  if (ans == "No solution") {
    cout << "No solution" << endl;
    return 0;
  }
  int l = 0;
  for (int i = 1; i < n;) {
    if (str[i] == '@') {
      if (i != pre) {
        ans += str.substr(l, (i - l + 2)) + ',';
        i++;
        l = i + 1;
      } else {
        ans += str.substr(l, (n - l));
        break;
      }
    }
    i++;
  }
  if (l == 0 && pre == -2) ans = "No solution";
  cout << ans << endl;
  return 0;
}
