1090M - The Pleasant Walk - CodeForces Solution

#include<iostream>
#include <string>
#include<sstream>
#include<algorithm>
#include<cmath>
#include<vector>
#include<deque>
#include<queue>
#include<stack>
#define endl "\n"
using namespace std;
using ll = long long;
bool cmb(pair<vector<ll>,ll>&v, pair<vector<ll>, ll>&v2){
	return (v.first > v2.first);
}
int main()
{
	ll a, b;
	cin >> a >> b;
	vector<ll>v(a);
	for (int i = 0; i < a; i++)cin >> v[i];
	ll counter = 0,mx=0;
	for (int i = 0; i < a-1; i++) {
		if (v[i] != v[i + 1]){
			if (counter == 0)counter++;
			counter++;
		}
		else{
			mx = max(mx, counter);
			counter = 0;
		}
	}
	
	if (mx == 0 && counter == 0)cout << 1 << endl;
	else if (counter != 0)cout << max(mx,counter) << endl;
	else cout << mx << endl;
}