func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     ios_base::sync_with_stdio(false);     cin.tie(NULL);     cout.tie(NULL);     ;     string s;     cin >> s;     if (s[0] ==  @  || s.back() ==  @  || (s.find( @ ) == -1)) {       cout <<  No solution ;       return 0;     }     vector<int> v;     for (int i = 0; i < s.size(); i++) {       if (s[i] ==  @ ) v.push_back(i);     }     for (int i = 1; i < v.size(); i++) {       if (v[i] - v[i - 1] < 3) {         cout <<  No solution ;         return 0;       }     }     int pre = 0;     for (int i = 0; i < v.size(); i++) {       for (int j = pre; j <= v[i] + 1; j++) {         cout << s[j];       }       if (i + 1 != v.size()) cout <<  , ;       pre = v[i] + 2;     }     for (int i = pre; i < s.size(); i++) cout << s[i];     return 0;   }   