#include <bits/stdc++.h>
using namespace std;
int main() {
stack<string> st;
st.push("f");//0
st.push("i");//1
st.push("r");//2
st.push("A");//3
cout << st.top() << endl;
//int n = st.size();
while(!st.empty()){ //1 or 0
cout << st.top();
st.pop();
}
return 0;
}
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