#include<string>

#include<iostream>

#include<algorithm>

#define lson l,m,rt<<1

#define rson m+1,r,rt<<1|1

using namespace std;

const int maxn = 2e5 + ;

int tree[maxn << ];

void build(int l, int r, int rt)

{

    if (l == r){

        cin >> tree[rt];

        return;

    }

    int m = (l + r) >> ;

    build(lson);

    build(rson);

    tree[rt] = max(tree[rt << ], tree[rt <<  | ]);

}

void update(int x, int ans, int l, int r, int rt)

{

    if (l == r){

        tree[rt] = ans;

        return;

    }

    int m = (l + r) >> ;

    if (x <= m)update(x, ans, lson);

    else update(x, ans, rson);

    tree[rt] = max(tree[rt << ] , tree[rt <<  | ]);

}

int query(int L, int R, int l, int r, int rt)

{

    if (L <= l&&r <= R){

        return tree[rt];

    }

    int m = (l + r) >> , ans = ;

    if (L <= m)ans = max(ans, query(L, R, lson));

    if (R > m)ans = max(ans, query(L, R, rson));

    return ans;

}

void Print(int l, int r, int rt)

{

    if (l == r){

        cout << rt << " = " << tree[rt] << endl;

        return;

    }

    cout << rt << " = " << tree[rt] << endl;

    int m = (l + r) >> ;

    if (l <= m)Print(lson);

    if (r > m)Print(rson);

}

int main()

{

    std::ios::sync_with_stdio(false);

    int n, q;

    while (cin >> n >> q){

        build(, n, );

        string flag; int i, j;

        while (q--){

            cin >> flag >> i >> j;

            if (flag == "U"){

                update(i, j, , n, );

            //    Print(1, n, 1);

            }

            else if (flag == "Q"){

                cout << query(i, j, , n, ) << endl;

            }

        }

    }

    return ;

}