Optimal Page Replacement Algorithm

 //OPTIMAL PAGE REPLACEMENT ALGORITHM  
 #include <stdio.h>  
 #include <conio.h>  
 int main()  
 {  
   int n, rss, fa[20], rsa[50], ta[20]; //n-No_of_Frames  
   //rss->Reference_String_Size::fa->Frame_Array  
   //rsa->Reference_String_Array::ta->Temporary_Array  
   int i,j,k, d,pfc=0,npf, cp,ff=0;  
   //d-distance[How soon a page will be used again?]  
   //cp->Current_Position :: ff->Frames_Filled ::pfc->Page_Fault_Count  
   //npf:NO_Page_Faults [0-False, 1-True]  
   printf("Enter number of frames: ");  
   scanf("%d", &n);  
   printf("Enter number of pages in reference string: ");  
   scanf("%d", &rss);  
   printf("Enter Reference string:\n");  
   for(i=0; i<rss; i++)  
     scanf("%d",&rsa[i]);  
   for(i=0;i<n;i++)  
   {  
     fa[i]=-1;  
     ta[i]=999;  
   }  
   printf("\nCURRENT_PAGE\t\tPAGES_IN_FRAME\t\tPAGE_FAULT_OCCURED?\n");  
   for(i=0; i<rss; i++)  
   {  
     printf("\n\t%d\t\t",rsa[i]);  
     npf=0;  
     for(j=0;j<n;j++)  //Checking for the page in FRAME ARRAY  
     {  
       if(fa[j]==rsa[i])  
       {  
         npf = 1;  
         printf("\t\t\t\tNO");  
         break;  
       }  
     }  
     if(npf==0)   // if page fault occurs  
     {  
       pfc++;  
       if(ff<n)  
       {  
         fa[ff]=rsa[i];  
         ff++;  
       }  
       else  
       {  
         for(k=0;k<n;k++)  
           ta[k]=999;  
         for(k=0; k<n; k++) //finding how near a page is  
         {  
           d = 0; // d-> distance  
           for(j=i+1;j<rss;j++)  
           {  
             if(fa[k]==rsa[j])  
             {  
               ta[k]=d;  
               break;  
             }  
             else  
               d++;  
           }  
         }  
         cp=0;  
         for(j=1;j<n;j++)  
         {  
           if(ta[cp]<ta[j])  
             cp=j; //cp->current position  
         }  
         fa[cp] = rsa[i];  
       }  
       for(j=0;j<n;j++)  
         printf("%d\t",fa[j]);  
       printf("\tYES");  
     }  
   }  
   printf("\nTotal no of pagefaults: %d",pfc);  
   return 0;  
 }