620C

#include <iostream>
#include <vector>
#include <algorithm>
#include <utility>
//no
using namespace std;
int n;
vector<int> a;

vector<int>::iterator f(vector<int>::iterator start, vector<int>::iterator cur)
{
    vector<int>::iterator result = cur;
    for(vector<int>::iterator i = start + 1; i != cur; i++)
    {
        vector<int>::iterator work = find(i + 1, cur, *(i));
        if (work != cur && (work - i) < (cur - start))
            result = work;
    }
    return result;
}

int main()
{
    scanf("%d", &n);
    for(int i = 0; i < n; i++)
    {
        int cur;
        scanf("%d", &cur);
        a.push_back(cur);
    }
    vector<int>::iterator it = a.begin();
    vector<pair<int, int>> res;
    int j = 0;
    res.push_back(make_pair(0, 0));
    while(j < n)
    {
        vector<int>::iterator cur = find(a.begin() + j + 1, a.end(), *(a.begin() + j));
        if (cur == a.end())
            ++j;
        else
        {
            cur = f(a.begin() + j, cur);
            res.push_back(make_pair(res.back().second + 1, cur - a.begin() + 1));
            j = cur - a.begin() + 1;
        }
    }
    if(res.size() == 1)
        cout << -1;
    else
    {
        res.back().second = n;
        printf("%d\n", res.size() - 1);
        for(int i = 1; i < res.size(); i++)
            printf("%d %d\n", res[i].first, res[i].second);
    }
    return 0;
}