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