Language: C

int main(){
  int n,i,j,a=0,c=0,g=0,t=0,flag=0;
  char order[6];
  char orders[2][6]={"insert","find"};
  char word[STR];
  char dicA[N][STR];
  char dicC[N][STR];
  char dicG[N][STR];
  char dicT[N][STR];
  
  
    scanf("%d",&n); 
  for(i=0;i<n;i++){
    flag=0;
    scanf("%s%s",order,word);
    
    if(strncmp(order,orders[0],6)==0){
      if(word[0]=='A'){
	strcpy(dicA[a],word);
	a++;
      }
      else if(word[0]=='C'){
	strcpy(dicC[c],word);
	c++;
      }
      else if(word[0]=='G'){
	strcpy(dicG[g],word);
	g++;
      }
      else if(word[0]=='T'){
	strcpy(dicT[t],word);
	t++;
      }
    }
    else if(strcmp(order,orders[1])==0){    
      
      if(word[0]=='A'){
	for(j=0;j<a;j++){
	  if(strcmp(&dicA[j][0],word)==0){
	    flag=1;
	    break;
	  }
	}
	
	if(flag==1)printf("yes\n");
	if(flag==0) printf("no\n");
      }
      else if(word[0]=='C'){
	for(j=0;j<c;j++){
	  if(strcmp(&dicC[j][0],word)==0){
	    flag=1;
	    break;
	  }
	}
	
	if(flag==1)printf("yes\n");
	if(flag==0) printf("no\n");
      }  
      
      else if(word[0]=='G'){
	for(j=0;j<g;j++){
	  if(strcmp(&dicG[j][0],word)==0){
	    flag=1;
	    break;
	  }
	}
	
	if(flag==1)printf("yes\n");
	if(flag==0) printf("no\n");
      }  
      
      else if(word[0]=='T'){
	for(j=0;j<t;j++){
	  if(strcmp(&dicT[j][0],word)==0){
	    flag=1;
	    break;
	  }
	}
	
	if(flag==1)printf("yes\n");
	if(flag==0) printf("no\n");
      }
    }
  }
  return 0;
}

Compiler output:
main.c: In function 'main':
main.c:5:13: error: 'STR' undeclared (first use in this function)
    5 |   char word[STR];
      |             ^~~
main.c:5:13: note: each undeclared identifier is reported only once for each function it appears in
main.c:6:13: error: 'N' undeclared (first use in this function)
    6 |   char dicA[N][STR];
      |             ^
main.c:12:5: error: implicit declaration of function 'scanf' [-Wimplicit-function-declaration]
   12 |     scanf("%d",&n);
      |     ^~~~~
main.c:1:1: note: include '<stdio.h>' or provide a declaration of 'scanf'
  +++ |+#include <stdio.h>
    1 | int main(){
main.c:12:5: warning: incompatible implicit declaration of built-in function 'scanf' [-Wbuiltin-declaration-mismatch]
   12 |     scanf("%d",&n);
      |     ^~~~~
main.c:12:5: note: include '<stdio.h>' or provide a declaration of 'scanf'
main.c:17:8: error: implicit declaration of function 'strncmp' [-Wimplicit-function-declaration]
   17 |     if(strncmp(order,orders[0],6)==0){
      |        ^~~~~~~
main.c:1:1: note: include '<string.h>' or provide a declaration of 'strncmp'
  +++ |+#include <string.h>
    1 | int main(){
main.c:17:32: warning: 'strncmp' argument 3 type is 'int' where 'long unsigned int' is expected in a call to built-in function declared without prototype [-Wbuiltin-declaration-mismatch]
   17 |     if(strncmp(order,orders[0],6)==0){
      |                                ^
<built-in>: note: built-in 'strncmp' declared here
main.c:19:9: error: implicit declaration of function 'strcpy' [-Wimplicit-function-declaration]
   19 |         strcpy(dicA[a],word);
      |         ^~~~~~
main.c:19:9: note: include '<string.h>' or provide a declaration of 'strcpy'
main.c:19:9: warning: incompatible implicit declaration of built-in function 'strcpy' [-Wbuiltin-declaration-mismatch]
main.c:19:9: note: include '<string.h>' or provide a declaration of 'strcpy'
main.c:23:9: warning: incompatible implicit declaration of built-in function 'strcpy' [-Wbuiltin-declaration-mismatch]
   23 |         strcpy(dicC[c],word);
      |         ^~~~~~
main.c:23:9: note: include '<string.h>' or provide a declaration of 'strcpy'
main.c:27:9: warning: incompatible implicit declaration of built-in function 'strcpy' [-Wbuiltin-declaration-mismatch]
   27 |         strcpy(dicG[g],word);
      |         ^~~~~~
main.c:27:9: note: include '<string.h>' or provide a declaration of 'strcpy'
main.c:31:9: warning: incompatible implicit declaration of built-in function 'strcpy' [-Wbuiltin-declaration-mismatch]
   31 |         strcpy(dicT[t],word);
      |         ^~~~~~
main.c:31:9: note: include '<string.h>' or provide a declaration of 'strcpy'
main.c:35:13: error: implicit declaration of function 'strcmp' [-Wimplicit-function-declaration]
   35 |     else if(strcmp(order,orders[1])==0){
      |             ^~~~~~
main.c:35:13: note: include '<string.h>' or provide a declaration of 'strcmp'
main.c:45:20: error: implicit declaration of function 'printf' [-Wimplicit-function-declaration]
   45 |         if(flag==1)printf("yes\n");
      |                    ^~~~~~
main.c:45:20: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:45:20: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
main.c:45:20: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:46:21: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
   46 |         if(flag==0) printf("no\n");
      |                     ^~~~~~
main.c:46:21: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:56:20: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
   56 |         if(flag==1)printf("yes\n");
      |                    ^~~~~~
main.c:56:20: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:57:21: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
   57 |         if(flag==0) printf("no\n");
      |                     ^~~~~~
main.c:57:21: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:68:20: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
   68 |         if(flag==1)printf("yes\n");
      |                    ^~~~~~
main.c:68:20: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:69:21: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
   69 |         if(flag==0) printf("no\n");
      |                     ^~~~~~
main.c:69:21: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:80:20: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
   80 |         if(flag==1)printf("yes\n");
      |                    ^~~~~~
main.c:80:20: note: include '<stdio.h>' or provide a declaration of 'printf'
main.c:81:21: warning: incompatible implicit declaration of built-in function 'printf' [-Wbuiltin-declaration-mismatch]
   81 |         if(flag==0) printf("no\n");
      |                     ^~~~~~
main.c:81:21: note: include '<stdio.h>' or provide a declaration of 'printf'