#include <bits/stdc++.h>
using namespace std;
using T = long long;
T op(T a, T b) { return a + b; }
struct SegmentTree {
	int n;
	vector<T> tree;
	T id;
	SegmentTree(int _n, T _id) : n(_n), tree(2 * n, _id), id(_id) {}
	void set(int i, T val) {
		for(tree[i + n] = val, i = (i + n) / 2; i > 0; i /= 2)
			tree[i] = op(tree[2 * i], tree[2 * i + 1]);
	}
	T query(int l, int r) {
		T lhs = T(id), rhs = T(id);
		for(l += n, r += n; l < r; l >>= 1, r >>= 1) {
			if(l & 1) lhs = op(lhs, tree[l++]);
			if(!(r & 1)) rhs = op(tree[r--], rhs);
		}
		return op(l == r ? op(lhs, tree[l]) : lhs, rhs);
	}
	pair<int, T> search(T v) { // Return the last position with query(i)<v; 0<=i<n.
		T sum = 0;
		int i = 1;
		while(i < n) {
			i *= 2;
			if(sum + tree[i] < v) sum += tree[i], ++i;
		}
		return {i - n, sum};
	}
};
int main() {
	int n, q;
	cin >> n >> q;
	vector<T> a(n);
	int m = n;
	for(int i = 1; i < m; i <<= 1)
		if(m & i) m += i;
	SegmentTree f(m, 0);
	T sum = 0;
	for(int i = 0; i < n; ++i) {
		cin >> a[i];
		sum += a[i];
		f.set(i, a[i]);
	}
	while(q--) {
		int i;
		T x;
		cin >> i >> x;
		f.set(i, x);
		sum += x - a[i];
		a[i] = x;
		pair<T, int> best = {std::numeric_limits<T>::max(), -1};
		const auto &p     = f.search((sum + 1) / 2);
		const int &m      = p.first;
		const T &v        = p.second;
		if(m > 0) best = min(best, {abs(abs((v - a[m - 1]) - (sum - v))-a[m-1]%2), m - 1});
		best = min(best, {abs(abs(v - (sum - v - a[m]))-a[m]%2), m});
		if(m + 1 < n) best = min(best, {abs(abs((v + a[m]) - (sum - v - a[m] - a[m + 1]))-a[m+1]%2), m + 1});
		cout << best.second << '\n';
	}
	return 0;
}