#include <iostream>
using namespace std;
int main()
{
    string a,kkk = "";
    int sum = 0,c = 0,d = 0;
    cin >> a;
    if(a[0] == '@' || a[a.size() - 1] == '@')
    {
        cout << "No solution\n";
        return 0;
    }
    for(int i = 0;i < a.size();i ++)if(a[i] == '@')d ++;
    if(a.size() <= 2 || d == 0)
    {
        cout << "No solution\n";
        return 0;
    }
    for(int i = 0;i < a.size();i ++)
    {
        if(a[i] == '@')
        {
            if(a[i + 1] == '@' || a[i + 2] == '@')
            {
                cout << "No solution\n";
                return 0;
            }
            else 
            {
                for(int j = i + 1;j < a.size();j ++)
                {
                    if(a[j] != '@') c ++;
                }
                if(c == a.size() - i - 1) 
                {
                    for(int j = sum;j <= a.size();j ++) kkk = kkk + a[j];
                    i = a.size();
                }
                else
                {
                    for(int j = sum;j <= i + 1;j ++) kkk = kkk + a[j];
                    kkk = kkk + ',';
                    sum = i + 2;
                }
                c = 0;
            }
        }
    }
    cout << kkk << "\n";
    return 0;
}