#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
vector<int> diff;
int main() {
fast
int N, Q;
string S, T;
cin >> N >> Q >> S >> T;
S = "#" + S;
T = "#" + T;
diff = vector<int>(N+1);
int even = 0, odd = 0;
for (int i = 1; i <= N; i++) {
diff[i] = (T[i] - S[i] + 26) % 26;
if (i % 2)
odd += diff[i];
else
even += diff[i];
}
if (even % 26 == odd % 26)
cout << "da\n";
else
cout << "ne\n";
while (Q--) {
int plc; char ch;
cin >> plc >> ch;
int last = diff[plc];
S[plc] = ch;
diff[plc] = (T[plc] - ch + 26) % 26;
if (plc % 2) {
odd += diff[plc] - last;
if (odd < 0)
odd += 26;
} else {
even += diff[plc] - last;
if (even < 0)
even += 26;
}
if (even % 26 == odd % 26)
cout << "da\n";
else
cout << "ne\n";
}
}
