//https://www.nowcoder.com/practice/de044e89123f4a7482bd2b214a685201?tpId=37&tqId=21231&rp=1&ru=/exam/oj/ta&qru=/exam/oj/ta&sourceUrl=%2Fexam%2Foj%2Fta%3FtpId%3D37&difficulty=undefined&judgeStatus=undefined&tags=&title=

#include <iostream>
#include <map>

using namespace std;

int main() {
    int n;
    while (cin >> n) {
        map<int, int> mp;
        int l = 0;
        int r = 0;

        while(n--){
            cin >> l >> r;
            mp[l]+=r;
        }

        for(auto c:mp)
            cout << c.first << " " << c.second << endl;
    }
}