#include <iostream>
#include <queue>
#include <map>
#include <set>
#include <cmath>
#include <cstring>
#include <algorithm>
#include <iomanip>
#include <stack>
#include <numeric>
#include <ctime>
#include <string>
#include <bitset>
#include <unordered_map>
#include <unordered_set>
#include <bits/stdc++.h>
#define il inline

using namespace std;
using ll = long long;
using ull = unsigned long long;

const ll N = 1e4 + 5, mod = 1e9 + 7, inf = 2e18;

il void solve() {
    int q;
    cin >> q;
    map<ll, ll>mp;
    while (q--) {
        ll op, add;
        cin >> op >> add;
        mp[op] += add;
    }
    for (auto [x, y] : mp) {
        cout << x << " " << y << '\n';
    }
}

int main() {
    ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);

    int t = 1;

    //cin >> t;

    while (t--) {

        solve();

    }

    return 0;
}