#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <getopt.h>

char* pre_process_fix(char argv[]){
   char* str1=malloc(strlen(argv)*sizeof(char));
   int j=0;
   for(int i=0;argv[i]!='\0';i++){
      if(argv[i]=='\\' && i+1<strlen(argv)){
         switch (argv[i+1]){
            case 'n': str1[j++]='\n';i++;break;
            case 't': str1[j++]='\t';i++;break;
         }
      }
      else str1[j++]=argv[i];
   }
   str1[j++]='\0';
   return realloc(str1,j*sizeof(char));
}

char* pre_process_filler(char argv[]){
   if(strlen(argv)==3 && argv[1]=='-'){
      char *str1 = malloc( (argv[2] - argv[0]) * sizeof(char) );
      int v=argv[0];
      for(int i=0 ; v <= argv[2]; i++){
         str1[i]=v++;
      }
      argv=str1;
   }
   return argv;
}

char* pre_process_complete_str2(char argv1[],char argv2[]){
   if(strlen(argv1) > strlen(argv2)){
      int i;
      char *temp = malloc(strlen(argv1)*sizeof(char));

      for(i=0; argv2[i]!='\0'; i++){
         temp[i]=argv2[i];
      }

      for(; i<strlen(argv1);i++){
         temp[i]=temp[i-1];
      }

      argv2=temp;
   }
   return argv2;
}

void rep_print(int argc,char *argv[]){
   argv[2] = pre_process_fix(argv[2]);
   argv[2] = pre_process_filler(argv[2]);

   if(argc==4){
      argv[3] = pre_process_fix(argv[3]);
      argv[3] = pre_process_filler(argv[3]);
      argv[3] = pre_process_complete_str2(argv[2],argv[3]);

      char c,rep=-1,subs=-1;
      int found,rep_found=0;
      while((c=getchar())!=EOF){
         found=-1;
         if(c==subs) found=1;
         for(int i=0;argv[2][i]!='\0';i++){
            if(c==argv[2][i]){
               subs=argv[3][i];
               found=i;
               break;
            }
         }
         if(found!=-1){
            if(c!=rep&&rep_found!=1&&c!=subs) {
               putchar(subs);
               rep=c;
               rep_found=1;
            }
         }
         else {
            putchar(c);
            rep=c;
            rep_found=0;
            subs=-1;
         }
      }
      exit(0);
   }

   char c,rep=-1;
   int found=0;
   while((c=getchar())!=EOF){
      found=0;
      for(int i=0;argv[2][i]!='\0';i++){
         if(c==argv[2][i]) found=1;
      }
      if(found==1&&c==rep) rep=c;
      else {
         putchar(c);
         rep=c;
      }
   }
   exit(0);
}

void del_print(char argv[]){
   argv = pre_process_fix(argv);
   argv = pre_process_filler(argv);

   int found=0;
   char c;
   while((c=getchar())!=EOF){
      found=0;
      for(int i=0;argv[i]!='\0';i++){
         if(c==argv[i]){
            found=1;
            break;
         }
      }
      if(found==0) putchar(c);
   }
   exit(0);
}

void def_print (int argc, char *argv[]){
   argv[1] = pre_process_fix(argv[1]);
   argv[2] = pre_process_fix(argv[2]);
   argv[1] = pre_process_filler(argv[1]);
   argv[2] = pre_process_filler(argv[2]);
   argv[2] = pre_process_complete_str2(argv[1],argv[2]);

   int found=0;
   char c;
   while((c=getchar())!=EOF){
      found=0;
      for(int i=0;argv[1][i]!='\0';i++){
         if(c==argv[1][i]){
            putchar(argv[2][i]);
            found=1;
            break;
         }
      }
      if(found==0) putchar(c);
   }
   exit(0);
}

int main(int argc, char *argv[]){
   int c;
   while((c = getopt(argc,argv,"sd:"))!=-1){
      switch(c){
         case 's': rep_print(argc,argv);
         case 'd': del_print(optarg);
      }
   }
   def_print(argc,argv);
}