#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; typedef long long LL; typedef unsigned long long ULL; #define MEM(a,b) memset((a),(b),sizeof(a)) const LL INF = 1e9 + 7; const int N = 2e5 + 10; int main() { //freopen("input.txt", "r", stdin); //freopen("output.txt", "w", stdout); string s1, s2; cin >> s1 >> s2; if (s1.length() < s2.length() || s1.length() > s2.length() + 1) puts("?"), exit(0); for (int i = 0; i < s2.length(); i++) cout << s1[i] << s2[i]; if (s1.length() > s2.length()) cout << s1.back(); cout << endl; return 0; }