Contest1342/A.cpp

#include <bits/stdc++.h>
using namespace std;
typedef long long LL;
 
const int MAXN = 2e6 + 10;
LL a[MAXN];
 
int main() {
    int n = 15;
    scanf("%d", &n);
    for (int i = 1; i <= n; i++)a[i] = i;
    partial_sum(a, a + n + 1, a);
    for (int i = 0; i <= n; i++) {
        LL x = a[i];
        LL key = x + n;
        int pos = lower_bound(a + i + 2, a + n + 1, key) - a;
        if (a[pos] == key) {
            printf("%d %d\n", i + 1, pos);
        }
    }
    return 0;
}