#pragma GCC optimize("Ofast")
#pragma GCC optimize("unroll-loops")
#pragma GCC optimize("fast-math")
#pragma GCC target("tune=native")
#include <bits/stdc++.h>
using namespace std;
constexpr int MAXN = 1000001;
constexpr int MOD = 26;
int n, q;
string s1, s2;
int x[MAXN], y[MAXN];
inline int mod26(int value) {
return (value % MOD + MOD) % MOD;
}
int main() {
ios_base::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
cin >> n >> q >> s1 >> s2;
y[1] = mod26(s2[0] - s1[0]);
x[1] = y[1];
for (int i = 2; i <= n; ++i) {
y[i] = mod26(s2[i - 1] - s1[i - 1]);
x[i] = mod26(y[i] - x[i - 1]);
}
cout << (x[n - 1] == y[n] ? "da" : "ne") << '\n';
while (q--) {
int pos; char c;
cin >> pos >> c;
if (pos == n) {
s1[n - 1] = c;
y[n] = mod26(s2[n - 1] - s1[n - 1]);
} else {
int delta = mod26(s1[pos - 1] - c);
s1[pos - 1] = c;
if ((n - 1 - pos) % 2 == 0)
x[n - 1] = mod26(x[n - 1] + delta);
else
x[n - 1] = mod26(x[n - 1] - delta);
}
cout << (x[n - 1] == y[n] ? "da" : "ne") << '\n';
}
return 0;
}
