CppPrimer_ex5_21

#include <iostream>
using namespace std;

int main() {
    string s1,old;
    
    while(cin>>s1) {

        if (old==s1) 
            break;
        else 
            old = s1;
    }
    
    if (s1 != old && cin.eof()) cout << "no repeated." << endl;
    else cout << s1 << " occurs twice in succession." << endl;
    
    return 0;
}