%{
    #include<stdio.h>#include<string.h>
     int i;
 %}
 
 %%
  [a-z A-Z]* 
    {for(i=0;i<=yyleng;i++)
      {if((yytext[i]=='a')&&(yytext[i+1]=='b')&&(yytext[i+2]=='c'))
            {
              yytext[i]='A';yytext[i+1]='B';yytext[i+2]='C';
            }
 
        }
        printf("%s",yytext);
 
     }
     [\t]* return;
     .* {ECHO;}
     \n {printf("%s",yytext);}
     %%
 
     int main()
     {
       yylex();
     }
 
     int yywrap()
     {
         return 1;
     }

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