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#include <cstdio>

int main()
{
  int n, p = 0, q = 0, u = 0, v = 0;
  scanf("%i", &n);
  for (int i = 0; i<n; i++)
  {
    int a, b;
    scanf("%i", &a);
    if (u++ && (i%2? a>=b: a<=b)) p++, u = 0;
    if (v++ && (i%2? a<=b: a>=b)) q++, v = 0;
    b = a;
  }
  printf("%i\n", p<q? p: q);
  return 0;
}