Определить порядковый номер числа, отличного от остальных

 #include <iostream>
#include <cmath>
using namespace std;
int main()
{
    int a, b, c, d;
    cout << "A, B, C, D" << endl;
    cin >> a >> b >> c >> d;
    if (a != b && a != c && a != d && b != c && b != d && c != d)
        cout << "different" << endl;
    else if (a == b && b == c && a == c && a == d && b == d && c == d)
        cout << "the same" << endl;
    else
        cout << ((a != b && b == c && c == d)) ? 1 : ((a == d) ? 2 : 3) << endl;
    system("pause");
}

cout << ((a != b && b == c && c == d) ? 1 : ((a == d) ? 2 : 3)) << endl;

#include <iostream>
#include <cmath>
using namespace std;
int main()
{
int a, b, c, d;
cout << "A, B, C, D" << endl;
cin >> a >> b >> c >> d;
if (a != b && a != c && a != d && b != c && b != d && c != d)
cout << "different" << endl;
else if (a == b && b == c && a == c && a == d && b == d && c == d)
cout << "the same" << endl;
else
cout << ((a != b && b == c && c == d)) ? 1 : ((a == d) ? 2 : 3) << endl;
system("pause");
}

cout << "Nomer: " << (a==b ? (a==c ? 3 : 2 ) : (a == c ? 1 : 0)) << endl; // [0;3]

#include <iostream>
#include <cmath>
using namespace std;
int main()
{
   int a[4],i;
   cout << "A, B, C, D" << endl;
   for(i=0;i<4;i++)
      cin >> a[i];
   int num=0;
   for(i=1;i<4;i++)
   {
        if(a[i]!=a[num];
        break;
   }
   if(i==4)
      cout << "all number is the same" << endl;
   if(i==2 %%i==3)
      cout<<i<<" number is another="<<a[i]<<endl;
   else if(a[2]!=a[num])
      cout<<1<<" number is another="<<a[1]<<endl;
   else
      cout<<0<<" number is another="<<a[0]<<endl;
 
   system("pause");
}

#include <iostream>
 
using namespace std;
 
 
int main()
{
   int A=4,B=5,C=4,D=4;
   (A==B ||  A==C || A==D)? cout<<"" : cout<<'A'-'@';
   (B==A ||  B==C || B==D)? cout<<"" : cout<<'B'-'@';
   (C==A ||  C==B || C==D)? cout<<"" : cout<<'C'-'@';
   (D==A ||  D==B|| D==C)? cout<<"" : cout<<'D'-'@';
 
   system("pause>0");
   return 0;
   }