#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define MOD 998244353
void solve()
{
ll n, q, sm = 0, p;
cin >> n >> q;
string s, t;
cin >> s >> t;
char c;
for (int i = 0; i < n; i++)
{
if (i & 1)
{
sm = sm - s[i] + t[i];
}
else
{
sm = sm + s[i] - t[i];
}
}
if (sm % 26 == 0)
{
cout << "da" << '\n';
}
else
{
cout << "ne" << '\n';
}
for (int i = 0; i < q; i++)
{
cin >> p >> c;
p--;
if ((p & 1) == 0)
{
sm = sm - s[p] + t[p];
}
else
{
sm = sm + s[p] - t[p];
}
s[p] = c;
if (p & 1)
{
sm = sm - s[p] + t[p];
}
else
{
sm = sm + s[p] - t[p];
}
if (sm % 26 == 0)
{
cout << "da" << '\n';
}
else
{
cout << "ne" << '\n';
}
}
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int tests = 1;
// cin >> tests;
for (int i = 1; i <= tests; i++)
{
// cout << "Case #" << i << ": ";
solve();
}
return 0;
}
