C++估數字

各位，我正左個c++的估數字game，但係估唔中後唔識叫人重新輸入，應該點攪？


my code:

#include <cstdlib>
#include <iostream>
#include <time.h>

using namespace std;

#define START 1
#define END 100

int main(){

int ans;
int guesstime;
int num;


srand( (unsigned)time(NULL) );
ans = rand() % 100 + 1;
guesstime = 0;


cout << "Please guess a number: \n";
cin >> num;


if (num == ans){
cout << "Congratulations! you use " << guesstime << " time to win it!! \n\n";
}

else if (num > ans){
cout << "Sorry, the number you guess is too large. \n\n" << endl;
}

else if (num < ans){
cout << "Sorry, the number you guess is too small. \n\n" << endl;
}


system("PAUSE");
return 0;
}