Multiple stack handling using single array

mult_stack.c

#include<stdio.h>
#define MAX 10
int arr[MAX],top1=-1,top2=MAX-1;
void push_stack1(int item)
{
          if(top1<top2)
          {
             top1=top1+1;
             arr[top1]=item;
          }
else
    printf("\nstack is overflow ");
}
void push_stack2(int item)
         {
            if(top1<top2-1){ 
             top2=top2-1;
             arr[top2]=item;
}
           else
           printf("\n stack overflow ");
           }
void pop_stack1()
{            int temp;
             if(top1>=0)
{
             temp=arr[top1];
             top1=top1-1;
}
         else
printf(" \nstack under flow");
}
  void pop_stack2()
{
                 int temp;
                 if(top2>=MAX-1)
{
                temp=arr[top2];
                top2=top2+1;
}
                 else

                 printf("\n underflow");
}     
void display_1()
{int i


          for(i=0;i<=top1;i++)
           printf("\n%d",arr[i]);
}
void display_2()
{int i;
         for(i=MAX-1;i>=top2;i--)
         printf("\n%d",arr[i]);
}       
int main()
{
int ch;
printf("\n 1:stack1 push \n 2: stack2push\n 3:stack1p0p\n 4: stack2pop \n 5:stack1display  \n 6: stack2display");
while(1)
{
printf("\n enter choice");
scanf("%d",&ch);
switch(ch)
{
case 1:
        {
         int data;
       printf("\n enter data for stack1");
       scanf("%d",&data);
        push_stack1(data);
       break;
}
case 2:
{
int data;
printf("\n enter data for stack2");
scanf("%d",&data);
push_stack2(data);
break;
}
case 3:
{
pop_stack1();
break;
}
case 4:
{
pop_stack2();
break;
}
case 5:
{
display_1();
break;
}
case 6:
{
display_2();
}
default:
printf("\n invalid choice");


}

      }
      return 0;
      }