//Oh? You're Approaching Me?
#include <bits/stdc++.h>
using namespace std;
//
#define int long long
typedef long long ll;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
// #pragma GCC optimize("O3,unroll-loops")
#define migmig ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define pb push_back
#define F first
#define S second
#define SZ(x) ll((x).size())
#define all(x) (x).begin(), (x).end()
#define cl clear
#define endl '\n'
#define deb(x) cerr << #x << " = " << x << '\n'
#define dokme(x) {cout << x << endl; return;}
#define wtf cout << "[ahaaaaaaaaaaaaaaaa]" << endl;
const int maxn = 1e6 + 10;
const int mod = 998244353;
const int inf = 1e18 + 5;
const int LOG = 31;
#define mid ((l + r) / 2)
#define lc (id * 2)
#define rc (lc + 1)
//g++ main.cpp -o main && main.exe
int n, q;
string s1, s2;
signed main() {
migmig;
cin >> n >> q;
cin >> s1 >> s2;
int val1 = 0, val2 = 0;
s1 = '!' + s1;
s2 = '!' + s2;
for (int i =1 ; i <= n; i++) {
if (i & 1)
val2 += s2[i];
else
val2 -= s2[i];
(val2 += 26 * 10) %= 26;
if (i & 1)
val1 += s1[i];
else
val1 -= s1[i];
(val1 += 26 * 10) %= 26;
}
if (val1 == val2)
cout << "da" << '\n';
else
cout << "ne" << '\n';
while (q--) {
int i;
char c;
cin >> i >> c;
if (i & 1) {
val1 -= s1[i];
s1[i] = c;
val1 += s1[i];
}
else {
val1 += s1[i];
s1[i] = c;
val1 -= s1[i];
}
(val1 += 26 * 10) %= 26;
if (val1 == val2)
cout << "da" << '\n';
else
cout << "ne" << '\n';
}
}
