Depth First Search not working

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

struct node{
	int vertex;
	int initial,end;
	struct node *next;
} *arr[50], *p, *q, *p2, *p3;

int visited[50]={0};
int t=1;

void DFS_main(int);
void DFS(struct node *);

int main(){
	int u,v,n,i;
	
	scanf("%d",&n);
	
	for(i=1;i<=n;i++){	
		arr[i]=(struct node *)malloc(sizeof(struct node));
		arr[i]->vertex=i;
		arr[i]->next=NULL;
	}
	
	while(5){
		scanf("%d%d",&u,&v);
		
		if(u==-1&&v==-1)
			break;
			
		p=arr[u];
		
		while(p->next!=NULL)
			p=p->next;
		
		q=(struct node *)malloc(sizeof(struct node));
		q->vertex=v;
		
		q->next=NULL;
		
		p->next=q;
	}
	p=arr[1];

	printf("The DFS for the Graph is\n");
	
	DFS_main(n);
	printf("out of dfs\n");
	printf("\n");
	
	for(i=1;i<=n;i++){
		//p2=arr[i];
		printf("%d  %d  %d\n",arr[i]->vertex,arr[i]->initial,arr[i]->end);
	}
	return 0;
}

void DFS_main(int n){
	int i;
	
	for(i=1;i<=n;i++){
		//printf("start vertex...%d\n",arr[i]->vertex);
		p=arr[i];
		
		if(visited[p->vertex]==0)
			
			DFS(p);
	}
}
void DFS(struct node *p1){
	
	visited[p1->vertex]=1;
	p1->initial=t++;
	
	printf("%d ---->",p1->vertex);
	
	p2=p1;
	while((p2=p2->next)!=NULL){
		if(visited[p2->vertex]==0){
			printf("%d  \n",p2->vertex);
			p3=arr[p2->vertex];
			DFS(p3);
		}	
			
	}
	
		p1->end=t++;
		//printf("  %d\n",p1->end); 
}
//