안녕하세요. 왈바 여러분 도와주세요.

스택과 큐에 관한 과제물 인데요..에러는 없는데 결과값이 이상합니다. 좀 도와주세요.ㅜ.ㅜ

제출은 둘째치고 답답해서 숨넘어가기 일보직전.......!@#$%^&*

고수님들 힘을 빌려 주세요~~~


#include<stdio.h>                

int top;                
int stack[3];
int Queue[3];
int data;
int head=0,tail=0;                        

push()                        
{
        stack[++top] = data;        
        return 0;
}

pop()                        
{
        stack[top--] = 0;                
        return 0;
}

stackwrite()                
{
        int i;
        printf("Stack : ");
        for(i=top;i>0;i--)                        
                printf("%3d",stack[i]);
        return 0;
}

Q_push()                
{
        Queue[tail++] = data;                
        return 0;
}

Q_pop()                        
{
        Queue[head++] = 0;                        
        return 0;
}

Q_write()                        
{
        int i;
        printf("\nQueue : ");                
        for (i=head;i<tail;i++)                        
                printf("%3d",Queue[i]);
        return 0;
}


void main()                        
{
        int ch;
        printf ("**************************************\n");
        printf ("1. add                2. delete        3.exit\n");
        printf ("**************************************\n");
        for(;;)
        {
                printf("\n\nChoose : ");
                scanf ("%d",&ch);
                printf("\n");
                if (ch==1)
                {
                        if (top > 2)
                        {
                                printf("overflow ...\n");
                                break;
                        }
                        printf("Input : ");
                        scanf("%3d",&data);
                        push();
                        Q_push();
                        stackwrite();
                        Q_write();
                }
                if (ch==2)
                {
                        if (top == 0)
                        {
                                printf("underflow ...\n");
                                break;
                        }
                        pop();
                        Q_pop();
                        stackwrite();
                        Q_write();
                }
                if (ch==3)
                {
                        break;
                }                        
                
        }
}