我写了这段代码，但它并不适用于所有数字。（RSA算法）

using namespace std;
int main () {
    int x;
    int p = 13;
    int q = 11;
    long n = p * q;
    long φ = (p - 1) * (q - 1);
    long e = φ - 1;
    long d = φ + e;
    cout<<"Plz enter a number.\n";
    cin>>x;
    long y = pow (x,e);
    long a = y % n;
    long b = pow (a,d);
    long c = b % n;
    cout<<"Original = "<<x<<endl;
    cout<<"Encrypted = "<<a<<endl;
    cout<<"Decrypted = "<<c<<endl;
    return 0;
}

对于某些数字，加密和解密显示相同数字，对于较大数字，它们显示随机数