#include <bits/stdc++.h>
using namespace std;
const int mxn = 1e6 + 10;
string str, target;
int n, q, shrek[mxn];
int main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cin >> n >> q;
cin >> str >> target;
int O = 0, E = 0, SUS = 0;
for(int i = 0; i < n; i++) {
int a = str[i] - 'a';
int t = target[i] - 'a';
shrek[i] = a;
if(i & 1) {
O = (O + a) % 26;
SUS = (SUS - t + 26) % 26;
}
else {
E = (E + a) % 26;
SUS = (SUS + t) % 26;
}
}
// cout << E << " - " << O << " = " << SUS << endl;
if(E == (O + SUS) % 26) cout << "da\n";
else cout << "ne\n";
while(q--) {
int i; char x;
cin >> i >> x;
x -= 'a';
i--;
if(i & 1) {
O = (O - shrek[i] + 26) % 26;
O = (O + x) % 26;
}
else {
E = (E - shrek[i] + 26) % 26;
E = (E + x) % 26;
}
shrek[i] = x;
if(E == (O + SUS) % 26) cout << "da\n";
else cout << "ne\n";
}
return 0;
}
