#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <bits/stdc++.h>
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef long double ldb;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef pair<ldb,ldb> pdd;
#define ff(i,a,b) for(int i = a; i <= b; i++)
#define fb(i,b,a) for(int i = b; i >= a; i--)
#define trav(a,x) for(auto& a : x)
#define sz(a) (int)(a).size()
#define fi first
#define se second
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
template<typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
// os.order_of_key(k) the number of elements in the os less than k
// *os.find_by_order(k) print the k-th smallest number in os(0-based)
const int mod = 1000000007;
const int inf = 1e9 + 5;
const int mxN = 1000005;
int n, q;
string s, t;
int d[mxN];
int r[mxN];
bool check(int a, int b){
int x = abs(a) % 26;
if(a < 0)a = 26 - x;
else a = x;
a %= 26;
int y = abs(b) % 26;
if(b < 0)b = 26 - y;
else b = y;
b %= 26;
return (a == b);
}
int main(){
cin.tie(0)->sync_with_stdio(0);
cin >> n >> q >> s >> t;
s = ' ' + s; t = ' ' + t;
ff(i,1,n){
r[i] = s[i] - t[i];
d[i + 1] = r[i] - d[i];
}
cout << (check(d[n], r[n]) ? "da" : "ne") << '\n';
while(q--){
int pos; char c;
cin >> pos >> c;
s[pos] = c;
int nw = s[pos] - t[pos];
int diff = nw - r[pos];
r[pos] = nw;
if(pos != n){
if((n - 1) % 2 == pos % 2)d[n] += diff;
else d[n] -= diff;
}
cout << (check(d[n], r[n]) ? "da" : "ne") << '\n';
}
return 0;
}
/*
3 1
bbc
ced
1 a
6 0
berlio
pjesni
// probati bojenje sahovski
*/
