#include<stdio.h>
#define gc getchar_unlocked
#include <string.h>
#define test int t;t=sscan();while(t--)
inline int sscan()
{
int n=0;
int ch=gc();
while(ch<'0'||ch>'9')
ch=gc();
while(ch>='0'&&ch<='9')
{
n=(n<<3)+(n<<1)+ch-'0';
ch=gc();
}
return n;
}
int main()
{
int top;
top=sscan();
int stack[1010],queue[1010];
int i,j;
for(i=0;i<top;i++)
{
stack[i]=sscan();
}
int dump=sscan();
int qind=-1,k=0,flag=1;
for(i=1;i<top+1;i++)
{
for(j=k;j<top;j++)
{
if(stack[j]==i)
{
stack[j]=0;
j++;
k=j;
break;
}
else if(queue[qind]==i)
{
queue[qind]=0;
qind--;
break;
}
else
{
queue[++qind]=stack[j];
if(qind>=1)
{
if(queue[qind]>queue[qind-1])
flag=2;
}
}
if(flag==2)
break;
}
if(flag==2)
break;
if(j>=top)
break;
}
if(flag==2)
else
return 0;
}
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