#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10;
typedef pair<int, int> pii;
pii a[N];
int pos[N];
int stdd;
int read() {
    int x = 0, f = 1; char ch = getchar();
    while (ch < '0' || ch > '9') { if (ch == '-') f = -1; ch = getchar(); }
    while (ch >= '0' && ch <= '9') { x = x * 10 + ch - '0'; ch = getchar(); }
    return x * f;
}
void write(int x) {
    if (x < 0) putchar('-'), x = -x;
    if (x >= 10) write(x / 10);
    putchar(x % 10 + '0');
}
void merge(int l, int r) {
    if (l == r) return;
    int mid = (l + r) >> 1;
    merge(l, mid);
    merge(mid + 1, r);
    int L = mid, R = mid;
    int i = mid, j = mid + 1;
    while (i >= l && pos[i] > stdd) L = i--;
    while (j <= r && pos[j] <= stdd) R = j++;
    if (L != R) {
        write(L); putchar(' '); write(R); putchar('\n');
        reverse(pos + L, pos + R + 1);
    }
}
void mergeSort(int l, int r) {
    if (l == r) return;
    int mid = (l + r) >> 1;
    stdd = mid;
    merge(l, r);
    mergeSort(l, mid);
    mergeSort(mid + 1, r);
}
int main() {
    int n; cin >> n;
    for (int i = 1; i <= n; i++) {
        cin >> a[i].first;
        a[i].second = i;
    }
    sort(a + 1, a + n + 1);
    for (int i = 1; i <= n; i++) {
        pos[a[i].second] = i;
    }
    mergeSort(1, n);
    write(-1); putchar(' '); write(-1); putchar('\n');
    return 0;
}