#include <bits/stdc++.h>
using namespace std;
char s[1024];
vector<int> q;
bool mark[1024];
int main() {
  scanf("%s", s);
  int len = strlen(s);
  if (s[0] == '@' || s[len - 1] == '@') {
    printf("No solution\n");
    return 0;
  }
  for (int i = 1; i < len; i++) {
    if (s[i] == '@') {
      q.push_back(i);
    }
  }
  if (q.size() == 0) {
    printf("No solution\n");
    return 0;
  }
  for (int i = 1; i < (int)q.size(); i++) {
    if (q[i] - q[i - 1] <= 2) {
      printf("No solution\n");
      return 0;
    }
    mark[q[i] - 2] = true;
  }
  for (int i = 0; i < len; i++) {
    printf("%c", s[i]);
    if (mark[i]) printf(",");
  }
  printf("\n");
  return 0;
}
