Nine degrees 1522 (OJ) problem

Only through the first case, do not know why.

#include <stdio.h> #include <stdlib.h> #include <iostream> #include <stack> using namespace std;
    Class mystack{public:stack<int> data;
    Stack<int> datamin;
            void Mypush (int tmp) {if (Data.empty ()) {Data.push (TMP);
            Datamin.push (TMP);
        Return
        } if (Data.top () >= tmp) {Datamin.push (TMP);
        }else{Datamin.push (Datamin.top ());
    } data.push (TMP);
        } void Mypop () {if (Data.empty ()) {return;
        } data.pop ();
    Datamin.pop ();
        } void Mymin () {if (!data.empty ()) {printf ("%d\n", Datamin.top ());
        }else{printf ("null\n");
 
}
    }
};
    int main () {int n;
    char flag;
    int datainput;
    int i;
    Mystack Stackdata; while (scanf ("%d", &n)! = EOF && n>=1 && n<=1000000) {if (n <= 0) {CoNtinue;
            } for (i=0; i<n; ++i) {scanf ("\n%c", &flag);
                if (flag = = = ' s ') {scanf ("%d", &datainput);
                Stackdata.mypush (Datainput);
            Stackdata.mymin ();
                }else if (flag = = ' O ') {stackdata.mypop ();
            Stackdata.mymin (); }} if (!stackdata.data.empty ()) {while (!stackdata.data.empty ()) {stackda
                Ta.data.pop ();
            Stackdata.datamin.pop ();
     
}}} return 0;
    }/************************************************************** problem:1522 User: Star River Language:c++ Result:wrong Answer ****************************************************************/