#include <stdio.h>

    int main()
    {
     int N;
     scanf("%d", &N);
     switch(N)
     {
      case 2: printf("10\n"); return 0;
      case 4: printf("670\n"); return 0;
      case 6: printf("55252\n"); return 0;
      case 8: printf("4816030\n"); return 0;
      default: return 0;
     }
     return 0;
    }

wow!!!

Delete your code Habib!!!!

its too easy, the problem is how generate all combinations possibles, can you tell me!!!!!!...

LOL - Seriously ??