#include <stdio.h>
int
main(
int
argc,
char
*argv[])
{
int
n,b,i,m,flag=0,a[20];
while
(
scanf
(
"%d"
,&n)!=EOF){
for
(i=0;i<n;i++){
scanf
(
"%d"
,&a[i]);
}
scanf
(
"%d"
,&m);
for
(i=0;i<n;i++){
if
(a[i]==m){
b=i;
flag=1;
break
;
}
}
if
(flag==1){
printf
(
"%d\n"
,b);
}
else
{
printf
(
"No\n"
);
}
flag=0;
}
return
0;
}