#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;
}