#include <bits/stdc++.h>
using namespace std;
int main() {
  string s, k[105];
  cin >> s;
  int n, i, j;
  for (i = 0; i < s.length(); i++) {
    if (s[i] == '@') {
      cout << "No solution";
      return 0;
    }
    j = i;
    while (s[j] != '@' && j < s.length()) {
      k[n] += s[j];
      j++;
    }
    if (j + 1 >= s.length() || s[j + 2] == '@') {
      cout << "No solution";
      return 0;
    }
    while (s[j + 1] != '@' && j < s.length()) {
      k[n] += s[j];
      j++;
    }
    i = j - 1;
    n++;
  }
  for (i = 0; i < n - 1; i++) {
    cout << k[i] << ",";
  }
  cout << k[n - 1];
}
