n , k = map(int,input().split())
a = list(map(int,input().split()))
l = a[k-1]
for i in a[k:]:
if i != l:
print(-1)
break
else:
for i,val in enumerate(reversed(a[:k-1])):
if val != l:
print(k-i-1)
break
else:
print(0)
#include<bits/stdc++.h>
using namespace std;
int a[100005],n,k,ans;
int main()
{
cin>>n>>k;
for(int i=1;i<=n;i++)
{
cin>>a[i];
}
for(int i=k;i<=n;i++)
{
if(a[i]!=a[k])
{
cout<<-1<<endl;
return 0;
}
}
for(int i=1;i<k;i++)
{
if(a[i]!=a[k])
{
ans=i;
}
}
cout<<ans<<endl;
return 0;
}120. Triangle | 102. Binary Tree Level Order Traversal |
96. Unique Binary Search Trees | 75. Sort Colors |
74. Search a 2D Matrix | 71. Simplify Path |
62. Unique Paths | 50. Pow(x, n) |
43. Multiply Strings | 34. Find First and Last Position of Element in Sorted Array |
33. Search in Rotated Sorted Array | 17. Letter Combinations of a Phone Number |
5. Longest Palindromic Substring | 3. Longest Substring Without Repeating Characters |
1312. Minimum Insertion Steps to Make a String Palindrome | 1092. Shortest Common Supersequence |
1044. Longest Duplicate Substring | 1032. Stream of Characters |
987. Vertical Order Traversal of a Binary Tree | 952. Largest Component Size by Common Factor |
212. Word Search II | 174. Dungeon Game |
127. Word Ladder | 123. Best Time to Buy and Sell Stock III |
85. Maximal Rectangle | 84. Largest Rectangle in Histogram |
60. Permutation Sequence | 42. Trapping Rain Water |
32. Longest Valid Parentheses | Cutting a material |