#include <iostream>
using namespace std;
string mingleStrings(string s1, string s2, int index) {
if (index >= s1.length()) {
return "";
} else {
string mingled = "";
mingled += s1[index];
mingled += s2[index];
mingled += mingleStrings(s1,s2,++index);
return mingled;
}
}
int main() {
cout << mingleStrings("cat", "dog", 0) << endl;
return 0;
}
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