text: #include <stdio.h>
  #include <stdlib.h>
  
  
  int main(void) {
      int A, B, C;
      scanf("%d %d %d", &A, &B, &C);
      
  
      // when temperature decreased
      if (A - B > 0) {
          if (B - C <= 0) {
              printf(":)\n");
          } else {
              if (  abs((B - C)) < abs((A - B)) ) {
                  printf(":)\n");
              } else {
                  printf(":(\n");
              }
          }
      }
  
      // when temperature increased
      if (A - B < 0) {
          if (B - C >= 0) {
              printf(":(\n");
          } else {
              if (  abs(B - C) < abs(A - B) ) {
                  printf(":(\n");
              } else {
                  printf(":)\n");
              }
          }
      }
  
      if (A - B == 0) {
          if ( B - C < 0) {
              printf(":)\n");
          } else {
              printf(":(\n");
          }
      }
  
      return 0;
  }