Find largest of three numbers in C

#include<stdio.h>
#include<conio.h>

int maximum(int x,int y)
{
                int z;
                z=(x>=y)?x:y;
                return z;
}

main()
{
      int a,b,c,d;
      printf("Enter three numbers:\n");
      scanf("%d%d%d",&a,&b,&c);
      d=maximum(a,b);
      printf("\nMaximum = %d",maximum(c,d));
      getch();
}