#include <stdio.h>
int main()
{
    int a,b,c;

    do
        scanf("%i",&a);
    while((a < -100) || (a > 100));

    do
        scanf("%i",&b);
    while((b < -100) || (b > 100));

    do
        scanf("%i",&c);
    while((c < -100) || (c > 100));


    if(a > b)
    {
        if(b > c)
        {
            if((b - c) < (a - b))
                printf(":)\n");
            else
                printf(":(\n");
        }
        else
            printf(":)\n");
    }
    else if(b > a)
    {
        if(c > b)
        {
            if((c - b) < (b - a))
                printf(":(\n");
            else
                printf(":)\n");
        }
        else
            printf(":(\n");
    }
    else if(c > b)
        printf(":)\n");
    else
        printf(":(\n");
    return 0;
}