#include <iostream>

#include <vector>

#include <queue>

#include <iterator>

#include <algorithm>

class Buf

{

public:

Buf(int size): _size(size), _proc(0) {}

~Buf() {}

void AddPackage(int time) {

int duration = 0;

std::cin >> duration;

if (_check(time))

_push(time, duration);

else

log.push_back(-1);

}

std::vector<int> log;

private:

std::queue<int> _buffer;

int _proc;

int _size;

bool _check(int time) {

if (_buffer.empty())

return true;

if (_buffer.front() <= time)

_buffer.pop();

if (_buffer.size() < _size)

return true;

return false;

}

void _push(int time, int duration) {

time = std::max(time, _proc);

log.push_back(time);

_buffer.push(time + duration);

_proc = std::max(time + duration, _proc);

}

};

int main(void)

{

int size = 0;

int n = 0;

std::cin >> size >> n;

if (n == 0)

return 0;

Buf buf(size);

for (int i = 0; i < n; ++i) {

int time = 0;

std::cin >> time;

buf.AddPackage(time);

}

for (auto i : buf.log)

std::cout << i << std::endl;

return 0;

}