This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
// #pragma GCC optimize("O3,unroll-loops")
// #pragma GCC target("avx2,bmi,bmi2,lzcnt,popcnt")
 
#include <bits/stdc++.h>
using namespace std;
 
#define ll long long
#define pii pair<int, int>
#define pll pair<ll, ll>
#define vi vector<int>
#define vl vector<ll>
#define vii vector<pii>
#define db long double
#define vll vector<pll>
#define endl '\n'
#define all(x) x.begin(), x.end()
#define fastio ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
 
#define int long long
void fmain(){
    int n, q;
    string s, t;
    cin >> n >> q >> s >> t;
    int sum = 0;
    for(int i = 0; i < n; i++){
        sum = (-sum + t[i] - s[i] + 26) % 26;
    }
    cout << (!sum ? "da" : "ne") << endl;
    while(q--){
        int idx;
        char c;
        cin >> idx >> c;
        int diff = c - s[idx - 1];
        s[idx - 1] = c;
        sum = (sum + 26 + diff + (n - idx + 1) % 2 * -2 * diff) % 26;
        cout << (!sum ? "da" : "ne") << endl;
    }
}
 
signed main(){
    int tmr = 1;
    // cin >> tmr;
    while(tmr--){
        fmain();
    }
}
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