This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx,avx2,fma")
#include <bits/stdc++.h>
using namespace std;
 
#define int long long
#define OYY LLONG_MAX
#define mod 998244353
#define faster ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define FOR for(int i=1;i<=n;i++)
#define mid (start+end)/2
#define lim 1000005
#define fi first
#define se second
int dizi[lim];
int pre[lim]; // gereksiz
int32_t main(){
	faster
	int n,q;cin>>n>>q;
	string a,b;cin>>a>>b;
	int bir=0,iki=0;
	FOR{
		dizi[i]=b[i-1]-a[i-1];
		if(i&1)bir+=dizi[i];
		else iki+=dizi[i];
	}
	
	if(bir==iki){
		cout<<"da"<<'\n';
	}
	else cout<<"ne"<<'\n';
	
	while(q--){
		int pos;char c;
		cin>>pos>>c;
		a[pos-1]=c;
		if(pos&1){
			bir-=dizi[pos];
			dizi[pos]=b[pos-1]-a[pos-1];
			bir+=dizi[pos];
		}
		else{
			iki-=dizi[pos];
			dizi[pos]=b[pos-1]-a[pos-1];
			iki+=dizi[pos];
		}
		if(bir==iki){
			cout<<"da"<<'\n';
		}
		else cout<<"ne"<<'\n';
	}
	return 0;
}
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