``
````#include
int main()
{
int n,i,j,x,y,t,p,l;
t=0;
l=0;
int a[20000],c[20000];
double b[20000];
for(i=0;i<20000;i++) {a[i]=c[i]=0;b[i]=1.1;}
scanf("%d",&n);
for(j=0;j"%d",&x);
if(x==0)
{ if(t==0) {l++;}
else {
c[l]=a[0];
b[l]=1.2;
l++;
for(p=1;pif(x==1)
{
scanf(" %d\n",&y);
a[t]=y;
t++;
}
}
i=0;
for(i=0;iif(b[i]==1.1)printf("invaild\n");
else printf("%d\n",c[i]);
}
return 0
}