#include<stdio.h>
#include<stdlib.h>
int main()
{
    int a,b,c;
    scanf("%d %d %d",&a,&b,&c);
    if(a > b ){
           if(b>c){
                a=abs(a);
                b=abs(b);
                c=abs(c);
        if((b-c) < (a-b)) printf(":)\n");
        else printf(":(\n");
           }
         else printf(":)\n");
    }
   else if(a < b) {
          if(b < c){
                a=abs(a);
                b=abs(b);
                c=abs(c);
        if((c-b) < (b-a)) printf(":(\n");
        else printf(":)\n");
    }
    else printf(":(\n");
   }
       else if(b < c) printf(":)\n");
        else printf(":(\n");
    return 0;
}