Pangrams Hacker rank solution in C

 #include <stdio.h>
int main()
{
               char st[1000],alpha;
               int i,flag;
               scanf("%[^\n]",st);
               for(alpha='a'; alpha <= 'z';alpha++)
               {
                              flag=0;
                              for(i=0;st[i]!='\0';i++)
                              {
                                             if(st[i]== alpha || st[i]== alpha-32)//in entire string if ‘a’ is present
                                             {
                                                            flag=1;
                                                            break;
                                             }
                              }
                              if(flag == 0) //in entire string ‘a’ is not present
                                             break;
               }
               if(flag == 0)
                              printf("not pangram");
               else
                              printf("pangram");
    return 0;
}

Output: