PROG-1072: number

#include <bits/stdc++.h>

using namespace std;
const int N = 5e5;
int ar[N+10];
int st = 1, n, re = 1;

int Index(int k){
    int idx = (st + ((re) * (k - 1) + n - 1) % n) + 1;
    if(idx > n) idx %= n;
    return idx;
}

int main(){

    int m;
    scanf("%d%d", &n, &m);

    for(int i=1;i<=n;i++) scanf("%d", &ar[i]);

    for(int i=1;i<=m;i++){
        char opr;
        scanf(" %c", &opr);
        if(opr == 'a'){
            int x, y;
            scanf("%d%d", &x, &y);
            swap( ar[ Index(x) ] , ar[ Index(y) ] );
        }
        else if(opr == 'b'){
            int x, k;
            scanf("%d%d", &x, &k);
            ar[ Index(x) ] = k;
        }
        else if(opr == 'c'){
            int k;
            scanf("%d", &k);
            st = Index(k);
            re = re * (-1);
        }
        else if(opr == 'q'){
            int x;
            scanf("%d", &x);
            printf("%d\n", ar[ Index(x) ]);
        }
    }

    return 0;
}