#include <bits/stdc++.h>
using namespace std;
long long int modInverse(long long int a, long long int m) {
  long long int m0 = m;
  long long int y = 0, x = 1;
  if (m == 1) return 0;
  while (a > 1) {
    long long int q = a / m;
    long long int t = m;
    m = a % m, a = t;
    t = y;
    y = x - q * y;
    x = t;
  }
  if (x < 0) x += m0;
  return x;
}
void pairsort(int a[], int b[], int n) {
  pair<int, int> pairt[n];
  for (int i = 0; i < n; i++) {
    pairt[i].first = a[i];
    pairt[i].second = b[i];
  }
  sort(pairt, pairt + n);
  for (int i = 0; i < n; i++) {
    a[i] = pairt[i].first;
    b[i] = pairt[i].second;
  }
}
void pairsortlli(long long int a[], long long int b[], long long int n) {
  pair<long long int, long long int> pairt[n];
  for (long long int i = 0; i < n; i++) {
    pairt[i].first = a[i];
    pairt[i].second = b[i];
  }
  sort(pairt, pairt + n);
  for (long long int i = 0; i < n; i++) {
    a[i] = pairt[i].first;
    b[i] = pairt[i].second;
  }
}
long long int binomialCoeff(long long int n, long long int k) {
  long long int C[k + 1];
  memset(C, 0, sizeof(C));
  C[0] = 1;
  for (long long int i = 1; i <= n; i++) {
    for (long long int j = min(i, k); j > 0; j--)
      C[j] = (C[j] + C[j - 1]) % 1000000007;
  }
  return C[k];
}
long long int power(long long int x, long long int y, long long int p) {
  long long int res = 1;
  x = x % p;
  while (y > 0) {
    if (y & 1) res = (res * x) % p;
    y = y >> 1;
    x = (x * x) % p;
  }
  return res;
}
long long int gcd(long long int a, long long int b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
long long int lcm(long long int a, long long int b) {
  return a * b / gcd(a, b);
}
long long int max(long long int a, long long int b) {
  if (a > b) return a;
  return b;
}
long long int min(long long int a, long long int b) {
  if (a < b) return a;
  return b;
}
long long int bins(long long int arr[], long long int l, long long int r,
                   long long int x) {
  if (r >= l) {
    long long int mid = l + (r - l) / 2;
    if (arr[mid] == x) return mid;
    if (arr[mid] > x) return bins(arr, l, mid - 1, x);
    return bins(arr, mid + 1, r, x);
  }
  return -1;
}
void swap(long long int* a, long long int* b) {
  long long int t;
  t = *a;
  *a = *b;
  *b = t;
}
int main() {
  ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  long long int n;
  cin >> n;
  long long int a[n];
  for (int i = 0; i < n; i++) cin >> a[i];
  if (n == 1 || n == 2) {
    cout << -1 << "\n";
    return 0;
  }
  long long int c = 0, d = 0;
  for (long long int i = 1; i < n; i++) {
    if (a[i] > a[i - 1]) c++;
    if (a[i] < a[i - 1]) d++;
  }
  if ((c == 0 && d == 0) || (c == 1 && d == 1 && n == 3 && a[0] == a[2]))
    cout << -1 << "\n";
  else if (c == 0) {
    for (long long int i = 1; i < n; i++) {
      if (a[i] < a[i - 1]) {
        cout << i << " " << i + 1 << "\n";
        return 0;
      }
    }
  } else if (d == 0) {
    for (long long int i = 1; i < n; i++) {
      if (a[i] > a[i - 1]) {
        cout << i << " " << i + 1 << "\n";
        return 0;
      }
    }
  } else if (c == 1 && d == 1) {
    if (n == 3) {
      cout << 1 << " " << 3 << "\n";
      return 0;
    }
    if (a[1] == a[2]) {
      for (long long int i = 3; i < n; i++) {
        if (a[i] > a[i - 1] || a[i] < a[i - 1]) {
          cout << i << " " << i + 1 << "\n";
          return 0;
        }
      }
    } else {
      cout << 2 << " " << 3 << "\n";
    }
  } else {
    if (c >= d) {
      for (long long int i = 1; i < n; i++) {
        if (a[i] > a[i - 1]) {
          cout << i << " " << i + 1 << "\n";
          return 0;
        }
      }
    } else {
      for (long long int i = 1; i < n; i++) {
        if (a[i] < a[i - 1]) {
          cout << i << " " << i + 1 << "\n";
          return 0;
        }
      }
    }
  }
}
