#include <bits/stdc++.h>
using namespace std;
#define debug(x) {cout << #x << ": "; for (auto it : x) cout << it << " ";cout << endl;}
#define fast ios::sync_with_stdio(0);cin.tie(0);
typedef long long ll;
#define f first
#define s second
#define MOD 1000000007
#define LOGN 15
#define MAXN 100005
int main() {
fast
int N, Q;
cin >> N >> Q;
string S, T;
cin >> S >> T;
int even = 0, odd = 0;
for (int i = 0; i < N; i+=2)
even += T[i] - S[i];
for (int i = 1; i < N; i+=2)
odd += T[i] - S[i];
if ((even % 26) == (odd % 26))
cout << "da\n";
else
cout << "ne\n";
while (Q--) {
int plc; char ch;
cin >> plc >> ch;
plc--;
if (plc % 2)
odd += S[plc] - ch;
else
even += S[plc] - ch;
if ((even % 26) == (odd % 26))
cout << "da\n";
else
cout << "ne\n";
}
}
