#include <bits/stdc++.h>
using namespace std;
int main() {
  string s;
  cin >> s;
  int a[300];
  int j = 0;
  int p;
  for (int i = 0; i < s.length(); i++) {
    if (s[i] == '@') {
      a[j] = i + 1;
      j++;
    } else {
      p = i + 1;
    }
  }
  if (j == 0) {
    cout << "No solution" << endl;
    return 0;
  }
  if (s[(s.length() - 1)] == '@' || s[0] == '@') {
    cout << "No solution" << endl;
    return 0;
  }
  int b[1000];
  int k = 0;
  for (int i = 0; i < j; i += 1) {
    int p = abs(a[i + 1] - a[i]);
    if (p <= 2 && j != 1) {
      cout << "No solution" << endl;
      return 0;
    }
    b[k] = a[i] + (int)abs(a[i + 1] - a[i]) / 2;
    k++;
  }
  int jj = 0;
  for (int i = 0; i < s.length(); i++) {
    cout << s[i];
    if ((i + 1) == b[jj] && (jj != k - 1)) {
      cout << ",";
      jj++;
    }
  }
  return 0;
}
