#include<cstdio>

#include<map>

#include<iostream>

#include<cstring>

using namespace std;

const int MAXN = 200000 + 10;

int a[MAXN];

int ma[MAXN << 2];

void build(int id, int L, int R){

    if(L == R){

        ma[id] = a[L];

    }

    else{

        int mid = L + (R - L) / 2;

        build(id << 1, L, mid);

        build(id << 1 | 1, mid + 1, R);

        ma[id] = max(ma[id << 1], ma[id << 1 | 1]);

    }

}

void update(int pos, int id, int L, int R, int value){

    if(L == R){

        ma[id] = value;

    }

    else{

        int mid = L + (R - L) / 2;

        if(pos <= mid) update(pos, id << 1, L, mid, value);

        else update(pos, id << 1 | 1, mid + 1, R, value);

        ma[id] = max(ma[id << 1], ma[id << 1 | 1]);

    }

}

int query(int l, int r, int id, int L, int R){

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

        return ma[id];

    }

    int ans = 0;

    int mid = L + (R - L) / 2;

    if(l <= mid) ans = max(ans, query(l, r, id << 1, L, mid));

    if(r > mid) ans = max(ans, query(l, r, id << 1 | 1, mid + 1, R));

    return ans;

}

int main(){

    int N, M;

    while(scanf("%d%d", &N, &M) == 2){

        memset(a, 0, sizeof a);

        memset(ma, 0, sizeof ma);

        for(int i = 1; i <= N; ++i){

            scanf("%d", &a[i]);

        }

        build(1, 1, N);

        while(M--){

            getchar();

            char c;

            scanf("%c", &c);

            int x, y;

            scanf("%d%d", &x, &y);

            if(c == 'Q'){

                printf("%d\n", query(x, y, 1, 1, N));

            }

            else if(c == 'U'){

                update(x, 1, 1, N, y);

            }

        }

    }

    return 0;

}