#include<bits/stdc++.h>
#include<fstream>
using namespace std;
#define sz(a) (int)a.size()
#define ALL(v) v.begin(), v.end()
#define ALLR(v) v.rbegin(), v.rend()
#define ll long long
#define pb push_back
#define forr(i, a, b) for(int i = a; i < b; i++)
#define dorr(i, a, b) for(int i = a; i >= b; i--)
#define ld long double
#define vt vector
#include<fstream>
#define fi first
#define se second
#define pll pair<ll, ll>
#define pii pair<int, int>
#define mpp make_pair
#define ull unsigned long long
const ld PI = 3.14159265359, prec = 1e-9;;
//using u128 = __uint128_t;
//const int x[4] = {1, 0, -1, 0};
//const int y[4] = {0, -1, 0, 1};
const ll mod = 1e9 + 19972207, pr = 31;
const int mxn = 5e5 + 5, mxq = 1e5 + 5, sq = 500, mxv = 10005;
//const int base = (1 <<18);
const ll inf = 1e9 + 5, neg = -69420, inf2 = 1e14;
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
// have fun!
int n, q;
string s, t;
int a[mxn + 1], b[mxn + 1];
void calc(){
int rem = 0, have = 0;
for(int i = 1; i < n; i++){
int need = ((b[i] - a[i]) - have + 26) % 26;
have = need;
}
if(((b[n] - a[n] + 26) % 26) == have){
cout << "da" << "\n";
}else{
cout << "ne" << "\n";
}
}
void solve(){
cin >> n >> q;
string s, t; cin >> s >> t;
for(int i = 1; i <= n; i++)a[i] = (s[i - 1] - 'a');
for(int i = 1; i <= n; i++)b[i] = (t[i - 1] - 'a');
calc();
while(q--){
int id; char c; cin >> id >> c; a[id] = (c - 'a');
calc();
}
}
signed main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
//freopen("i.inp", "r", stdin);
//freopen("i.out", "w", stdout);
int tt; tt = 1;
while(tt--){
solve();
}
return(0);
}
