#include <stdio.h>
int find_pattern(int *mem, int n) {
// Write your pointer-based logic here
int count = 0 ;
int flag = 0;
int index = 0;
for (int i = 1 ; i < n ; i ++)
{
if ( *(mem+ (i -1 )) + 1== *(mem+ i) )
{
if (flag == 0)
{
index = i - 1;
flag = 1;
}
count ++;
}
if (count >= 3)
{
return index;
}
}
return -1;
}
int main() {
int n, arr[100];
scanf("%d", &n);
for (int i = 0; i < n; i++) {
scanf("%d", &arr[i]);
}
int res = find_pattern(arr, n);
printf("%d", res);
return 0;
}
Input
8 2 4 5 6 9 11 12 14
Expected Output
1