let arr = []

while(line = readline()) {
    arr.push(line);
}

const length = arr[0];
let list = arr.slice(1, length + 1);

let newArr = [];
for (item of list) {
    let key = parseInt(item.split(' ')[0]);
    let value = parseInt(item.split(' ')[1]);
    newArr[key] = newArr[key] ? newArr[key] + value : value;
}

for (key in newArr) {
    if (newArr[key]) {
       print(key + ' ' + newArr[key]);
    }
}