#include <bits/stdc++.h>
using namespace std;
using T = long long;
struct FenwickTree { // queries are right-exclusive; 0-based
	int n;
	vector<T> tree;
	FenwickTree(int n) : n(n) { tree.assign(n + 1, 0); }
	T query(int r) { // [0,r)
		T s = 0;
		for(; r > 0; r -= (r & (-r))) s += tree[r];
		return s;
	}
	void update(int i, T v) {
		for(++i; i <= n; i += (i & (-i))) tree[i] += v;
	}
	pair<int, T> search(T v) { // Return the last position with query(i)<v; 0<=i<n.
		T sum = 0;
		int i = 0;
		for(int p = 1 << (8 * sizeof(int) - 1 - __builtin_clz(n)); p > 0; p >>= 1)
			if(i + p < n && sum + tree[i + p] < v) i += p, sum += tree[i];
		return {i, sum};
	}
};
int main() {
	int n, q;
	cin >> n >> q;
	vector<T> a(n);
	FenwickTree f(n);
	T sum = 0;
	for(int i = 0; i < n; ++i) {
		cin >> a[i];
		sum += a[i];
		f.update(i, a[i]);
	}
	while(q--) {
		int i;
		T x;
		cin >> i >> x;
		f.update(i, x - a[i]);
		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;
}