#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 l, int r) { return query(r) - query(l); } // [l,r)
	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;
	}
};
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;
		int l = 0, h = n - 1; // m in [l,h]
		pair<T, int> best = {std::numeric_limits<T>::max(), -1};
		while(l <= h) {
			int m = (l + h + 1) / 2;
			T ls  = f.query(m); // [0,m)
			T rs  = sum - ls - a[m];
			pair<T, int> p{abs(ls - rs), m};
			best = min(best, p);
			if(l == h) break;
			if(ls < rs) l = m + 1;
			if(ls >= rs) h = m - 1;
		}
		cout << best.second << '\n';
	}
	return 0;
}