Why you don't use C++ & STL? It more effectively then awful
pascal !!!


#include <iostream.h>
#include <ctype.h>

#include <stack>
using namespace std;

stack<char> st;

void flush_stack(){
    int n = st.size(), i;
    if (n>0) {
        for(i=0; i<n; ++i){
            cout<<st.top();
            st.pop();
        }
    }
}

int main () {
    char pch[1];

    while (1) {
        cin.read(pch, 1);
        if (cin.eof()) break;
        if (isalpha(*pch)) {
            st.push(*pch);
        } else {
            flush_stack();
            cout.write(pch, 1);
        }
    }
    flush_stack();

    return 0;
}