#include <bits/stdc++.h>
#define int long long
using namespace std;
const long long N = 2e5 + 5;
int a[N];
void solve()
{
    int n, q;
    string s, t;
    cin >> n >> q >> s >> t;
    int osum = 0;
    int esum = 0;
    for (int i = 0; i < n; i++)
    {
        if (i % 2 == 0)
            osum += s[i] - t[i];
        else
            esum += s[i] - t[i];
    }
    osum %= 26, esum %= 26;
    osum += 26, esum += 26;
    osum %= 26, esum %= 26;
    cout << ((osum == esum) ? "da" : "ne") << endl;
    int k;
    char c;
    for (int i = 0; i < q; i++)
    {
        cin >> k >> c;
        if (k % 2 == 0)
            osum -= s[i] - t[i];
        else
            esum -= s[i] - t[i];
        osum %= 26, esum %= 26;
        osum += 26, esum += 26;
        osum %= 26, esum %= 26;
        cout << ((osum == esum) ? "da" : "ne") << endl;
        s[k] = c;
        if (k % 2 == 0)
            osum += s[k] - t[k];
        else
            esum += s[k] - t[k];
        osum %= 26, esum %= 26;
        osum += 26, esum += 26;
        osum %= 26, esum %= 26;
    }
}
signed main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(NULL);
    cout.tie(NULL);
    int t = 1;
    // cin >> t;
    for (int i = 1; i <= t; i++)
    {
        // cout << "Case #" << i << ':' << ' ';
        solve();
        cout << endl;
    }
    return 0;
}
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