#include <iostream>
#include <vector>
using namespace std;
typedef long long ll;
const int maxn = 200005;
const int INF = 2e9;
struct node_data {
ll sum, prefix, suffix, res;
};

int n, a[maxn];
node_data merge_nodes(node_data A, node_data B) {
node_data C;

C.sum = A.sum + B.sum;
C.prefix = max(A.prefix, A.sum + B.prefix);
C.suffix = max(B.suffix, B.sum + A.suffix);

C.res = max(C.prefix, max(C.suffix, max(A.res, max(B.res, A.suffix + B.prefix))));

return C;
}

node_data make_node(int value) {
node_data C;
C.sum = value;
C.prefix = max(0, value);
C.suffix = max(0, value);
C.res = max(0, value);

return C;
}

node_data segment_tree[3 * maxn];

void build_tree(int L, int R, int node) {
if(L == R) {
segment_tree[node] = make_node(a[L]);
}
else {
int middle = (L + R) / 2;
build_tree(L, middle, 2 * node);
build_tree(middle + 1, R, 2 * node + 1);
segment_tree[node] = merge_nodes(segment_tree[2 * node], segment_tree[2 * node + 1]);
}
}

//L R i L R j L r
node_data query(int i, int j, int L, int R, int node) {
if(i <= L and R <= j) {
return segment_tree[node];
}
if(R < i or j < L) {
return make_node(-INF);
}

int middle = (L + R) / 2;

return merge_nodes(query(i, j, L, middle, 2 * node), query(i, j, middle + 1, R, 2 * node + 1));
}

void update(int idx, int new_value, int L, int R, int node) {
if(L == R) {
segment_tree[node] = make_node(new_value);
return;
}

int middle = (L + R) / 2;
if(idx <= middle) {
update(idx, new_value, L, middle, 2 * node);
}
else {
update(idx, new_value, middle + 1, R, 2 * node + 1);
}

segment_tree[node] = merge_nodes(segment_tree[2 * node], segment_tree[2 * node + 1]);
}
int main() {
ios_base::sync_with_stdio(false);
int q;

cin >> n >> q;

for(int i = 0; i < n; i++) {
cin >> a[i];
}
build_tree(0, n - 1, 1);

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

int x, y;
cin >> x >> y;
update(x - 1, y, 0, n - 1, 1);
cout << query(0, n - 1, 0, n - 1, 1).res << endl;

}



return 0;
}