Submission #983239

#	Time	Username	Problem	Language	Result	Execution time	Memory
983239		vjudge1	Street Lamps (APIO19_street_lamps)	C++17	0 / 100	50 ms	1208 KiB

street_lamps

#pragma GCC optimize("Ofast")
#define Magic ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
#define tsts int tststs; cin >> tststs; while(tststs--)
#include <bits/stdc++.h>
using namespace std;
using ull = unsigned long long;
using ll = long long;
using str = string;
#define sz(a) int(a.size())
#define ppf pop_front
#define ppb pop_back
#define pf push_front
#define pb push_back
#define x1 fukumean1
#define x2 fukumean2
#define y1 fukumean3
#define y2 fukumean4
#define ers erase
#define nxt print() // for new line
#define fix cout << fixed // for decimal numbers
struct custom_hash {
	static uint64_t splitmix64(uint64_t x) {
		// http://xorshift.di.unimi.it/splitmix64.c
		x += 0x9e3779b97f4a7c15;
		x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
		x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
		return x ^ (x >> 31);
	}
	size_t operator()(uint64_t x) const {
		static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
		return splitmix64(x + FIXED_RANDOM);
	}
};
void print() {cout << "\n";}
template <typename T>
void print(const T& arg) {
	cout << arg << " ";
}
template <typename T, typename... Args>
void print(const T& arg, const Args&... args) {
	cout << arg << " ";
	print(args...);
}
inline void debugMode() {
	#ifndef ONLINE_JUDGE
	freopen("in.txt", "r", stdin);
	freopen("out.txt", "w", stdout);
	#endif // ONLINE_JUDGE
}
const int INF = 1e9;
signed main() {
	Magic
	// debugMode();
	int n, q;
	cin >> n >> q;
	str c;
	cin >> c;
	int last[n] = {}, res[n] = {};
	for (int i = 0; i < n; i++) {
		if (c[i] == '0')
			last[i] = INF;
		else
			last[i] = 0;
	}
	for (int g = 1; g <= q; g++) {
		str s;
		cin >> s;
		if (s[0] == 't') {
			int x;
			cin >> x;
			x--;
			if (c[x] == '0') {
				c[x] = '1';
				last[x] = g;
			} else {
				c[x] = '0';
				res[x] += g - last[x] + 1;
				last[x] = INF;
			}
			continue;
		}
		int a, b, k = 0;
		cin >> a >> b;
		a--;
		b--;
		if (a + 1 == b) {
			int add = 0;
			if (last[a] != INF)
				add += g - last[a];
			cout << res[a] + add << "\n";
			continue;
		}
	}
}
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣠⠤⢲⣦⡀⠀⣠⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣀⣀⣀⣠⠖⠚⠓⠒⠒⠲⠿⣍⣛⣻⣦⣷⢠⣻⣀⠤⠤⣀⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣠⠔⡿⠓⠲⠬⢥⡤⠤⠤⠤⠤⣤⣀⣀⣈⣻⣿⣿⠓⠉⣀⡤⠔⢶⣻⡆⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣀⣤⢤⠞⠁⣼⠀⠀⠀⠀⠀⠀⠰⠶⢌⣽⡶⠟⢏⡁⢈⣉⣭⣷⡯⣝⠒⢦⣄⠙⠷⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⡾⣵⠿⣳⡟⠉⠉⠿⠀⠀⡀⠀⠀⣀⣀⣢⣾⣿⡚⠓⠒⠒⠒⠻⢿⣟⣧⡀⢠⣢⡻⠙⣄⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⡀⢿⣟⣲⢿⣷⢀⣤⣠⣄⣈⢿⣷⣤⣷⣻⡓⠒⠻⠭⢷⡄⠒⠲⢶⣦⣬⣻⣏⢦⡈⢿⣆⠘⡄⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢠⢖⣩⠷⢎⣙⣿⣿⣼⡼⣿⣟⣽⣻⢯⢿⠞⣌⠙⢳⡕⠀⠙⠲⣶⠤⢄⡠⣄⡈⠛⣿⣿⣧⢳⣌⢻⡆⡇⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠰⠗⠉⢀⣾⠟⠒⡿⣫⡿⡾⢫⢟⡏⠉⢸⡀⠑⢾⡆⢤⣻⣶⣤⣘⣲⣿⣶⡽⠿⣯⠲⣌⣇⢹⣷⣿⣆⠸⡇⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠈⠀⠀⡼⠀⣿⢣⣧⠋⣸⠀⣰⢀⣿⣆⠀⠰⣄⠙⣧⣨⣿⣿⣿⣯⣿⣦⠘⣷⡌⢻⡄⠿⣆⠟⣆⢇⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣀⠀⠀⠀⠀⠀⠀⠀⠀⡇⡼⣹⠈⢣⠆⡇⣰⣻⣼⣿⣽⣷⣦⣹⣿⣟⣯⠉⠘⣿⠏⠃⠀⣷⣽⡿⣾⡹⣷⣹⣧⡈⢺⡀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣠⢾⠟⠉⠀⠀⠀⠀⠀⠀⠀⠀⣷⣱⣽⡀⢸⣆⢳⣿⣇⣷⡿⠖⠿⠷⢦⣙⣆⠩⡗⠀⠀⠀⠀⠀⡯⠿⠳⣟⠻⣽⣄⢧⠈⠳⣷⡀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⣸⡇⡏⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣤⣿⣿⣷⣸⣿⡀⣿⣅⠛⠇⠀⠀⠀⠀⢈⠙⠂⠀⠀⠀⠀⠀⣸⣿⠀⢠⣜⢦⠘⢿⣮⣷⡀⠀⠙⢦⡀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⢯⣇⠙⢄⣀⠀⠀⠀⢀⣀⡠⣴⣾⣫⠵⠛⣿⣻⠿⣷⣹⣾⣷⡠⡀⠀⠀⠀⠻⠦⠀⣀⠔⠀⠀⣴⣿⣸⣧⡀⠳⣝⠳⢴⡙⢞⣏⠢⡀⠀⠹⡄⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⢀⣀⣀⣈⣻⣤⣀⠈⠉⠻⠿⢿⣺⣿⡵⣶⢶⣦⠀⠘⣿⢷⣾⢿⣿⡋⢙⣮⣄⡀⠀⠀⠉⠈⠀⠀⢀⢞⣿⣼⣿⣿⣿⣆⡀⠙⢦⣝⣮⠛⢷⡙⢆⠀⣷⠀⠀⠀⠀
///⠀⠀⠀⢠⡴⢟⣫⠤⠖⠒⠛⢛⣲⣿⣿⣿⠟⠋⢱⣿⣴⣷⣿⣹⢃⣀⣘⠃⢩⢿⣫⣥⣿⠧⢿⣿⣗⡶⣤⣄⣀⣴⣷⣻⣿⣿⠻⠘⣏⠛⢿⣦⣀⠱⢤⣉⡑⠛⠮⢿⣹⠀⠀⠀⠀
///⠀⢠⢖⠵⠊⠁⢀⡤⠖⣲⣿⣿⣟⣻⣿⣋⠀⠀⠈⢿⣿⡿⠟⣵⣿⣿⣿⣷⡏⠈⢿⡿⣷⣤⣼⢿⣿⣿⢶⣯⣭⣵⣾⢿⣿⠿⢦⡀⢹⠀⠈⣏⠉⠉⢻⣶⣯⡑⠦⣄⠈⠳⣄⠀
///⠀⠹⠁⠀⠀⣞⢁⡾⢽⣯⣝⣛⣛⣯⣭⣽⣿⣷⣶⣤⣤⣴⣿⣿⣿⣿⣿⣿⡀⣀⣼⣀⠈⠙⠛⠷⣾⡿⢿⡟⣿⠟⠁⣈⣥⡴⠾⠷⢾⡄⠀⣿⠀⠀⠈⢇⠘⣿⣤⣀⠑⢦⡘⢧⠀
///⠄⠀⠀⠀⠀⠈⠻⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⡿⢿⡿⠛⣻⢏⡽⣯⡄⠘⣏⣿⡏⠈⠙⠓⠶⣤⣀⠀⠙⢿⣿⡇⢀⡿⠋⠁⠀⢀⣀⣸⡇⠀⣟⣀⠀⠀⠀⠙⠃⣿⡎⠑⣤⡙⣌⡇
///⠀⠀⠀⠀⠀⠀⠀⠀⠙⢿⣿⣿⣿⣿⣿⣿⣿⡥⣖⡯⠖⢋⣡⡞⣼⣿⠀⠀⢹⣿⣷⠀⠀⣀⡀⠀⠉⠻⣦⠀⢿⣿⡿⠁⣠⡶⠟⠋⠉⠹⣆⣸⣿⣿⠀⣀⡤⣤⡀⣿⠇⠀⢸⠳⡜⡇
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣈⣿⣿⣿⣿⣿⣿⣏⢿⣗⠒⠊⠉⢸⠁⡿⡏⠀⢀⣿⡿⣁⠤⢶⣿⣽⡆⠀⠀⠘⢷⡈⠉⣡⠾⠋⠀⠀⣠⣆⢠⣿⣿⣿⡟⢀⣷⠒⢺⣧⡏⠀⠀⢸⠀⢹⣹
///⠀⠀⠀⠀⠀⠀⠀⡠⢪⠟⡽⠙⢶⣾⣿⣿⣿⣷⡻⣦⡀⠀⠀⢣⣇⡇⢀⡞⣸⠏⠁⠀⠀⡇⢻⡀⠀⠀⣾⣶⡟⣿⣥⡄⠀⠀⢠⣇⣼⡶⣿⣿⠋⣸⣾⣷⣚⣽⡟⠀⠀⠀⣏⠀⡼⣿
///⠀⠀⠀⠀⠀⢀⠎⡴⣣⣾⠟⣡⠞⢹⡿⣿⢿⣿⣿⣿⣷⣄⠀⠈⠻⡹⣼⠀⣿⡄⠀⠀⠀⠉⠻⣷⡀⠀⠙⠿⠇⣿⠿⠇⠀⠀⢠⡿⠋⢇⢹⣟⢷⠫⣿⣟⡿⠋⠀⠀⣠⣾⢞⡜⠁⡿
///⠀⠀⠀⠀⠀⡼⡼⣵⠏⡏⣰⠃⠀⢾⡇⠈⠻⣿⣮⡉⠹⣿⣧⣄⡀⠙⣇⠀⠸⣿⣄⡀⠀⠀⠀⠈⢉⣧⡴⠀⠠⡄⣀⡤⠤⠴⠋⠁⠀⠈⢻⣿⣾⣤⡿⠋⠀⠀⠀⣉⣽⠿⠋⠀⣰⠃
///⠀⠀⠀⠀⠀⣿⣽⠋⠀⡇⡇⠀⠀⠘⣷⢠⣶⢮⣻⣿⣦⠈⠛⠙⠹⣷⠘⢦⣤⣿⣳⣭⣑⣒⣒⣺⣿⢿⣀⣀⣀⣿⣧⣀⣀⣀⡤⠴⠒⣶⣿⣏⣾⡿⠁⠀⠀⠀⠉⠉⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⢻⡏⠀⠀⢳⣇⠀⠀⠀⠈⠈⣿⣾⣿⣿⣮⣿⣦⠀⠀⢿⣶⡫⣿⣿⣿⣿⣿⡹⣯⣊⠁⠉⠉⠉⠉⢙⣮⣷⣶⡤⣤⣶⣿⣿⣟⣾⢿⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠸⣿⣦⡀⠀⠙⠦⠀⠀⢀⣼⠿⣽⣿⣯⣷⣼⡷⢾⣻⣾⣿⠞⢿⢻⡷⠻⣿⣏⡙⢝⣻⡾⡖⠒⣻⣿⣿⣿⣿⣿⣿⣿⣿⣿⣿⡟⣎⠣⣀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠈⠁⠀⠀⠀⠀⣴⣋⣉⣩⣿⣿⢿⣟⣷⣾⣯⡟⢱⡇⠀⠘⣿⠣⡀⣈⣻⣿⣿⣿⣷⣷⣶⣿⣿⣟⠋⡿⣹⣿⣿⣿⣿⢟⣏⠺⠿⠶⠭⠷⠂⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢰⣿⣿⣿⣿⣿⣿⣿⢹⣮⣾⣿⡿⢋⣶⢸⡇⠀⠀⠈⢷⡑⠈⢻⣟⠛⠛⠿⠋⠙⠓⣭⣿⣹⣵⣿⣿⣿⣿⣿⠈⠻⣷⣄⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠈⠙⢟⣛⡭⠶⢾⡿⠃⠀⠀⢸⢹⣾⣇⠀⠀⠀⠀⠻⣟⣿⡏⠀⠀⠀⠀⢰⣿⣿⢿⡇⣿⣿⣿⣿⣟⡏⠀⠀⠀⠉⠙⠓⠒⠂⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢠⡟⠀⠀⠀⢰⣿⢸⣿⢿⡀⠀⠀⠀⠀⢸⣿⣣⠀⠀⠀⢠⣿⡟⣷⣾⣿⢿⣿⣿⣿⣿⡇⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣿⠁⠀⠀⠀⠘⡿⡿⢿⣏⣧⠀⠀⠀⢀⣾⣿⠿⠀⢀⣴⣿⣿⢿⡹⡇⣿⠈⣿⣿⡟⣾⠇⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢸⣿⡇⠀⠀⠀⠀⢳⢧⠈⢿⣿⠀⠀⢀⣼⣿⠕⠁⣠⣾⡿⣻⠏⠀⢹⣹⣿⣆⣿⣿⣿⣿⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣾⣿⣷⠀⠀⠀⠀⠈⣏⢧⠀⢻⣧⠶⣋⠿⠋⣀⣾⣟⣿⠞⠁⠀⠀⠀⢯⣿⣿⣿⣿⣿⡏⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢻⣿⣿⣇⠀⠀⠀⠀⠸⡜⣆⠈⢷⣿⠀⢠⣾⣿⠟⢻⡏⠀⠀⠀⠀⠀⠘⣿⣿⠏⣿⣿⠃⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢸⡻⣿⣿⣦⡀⠀⠀⠀⢧⠘⣆⠈⢷⠒⠛⢻⡿⠄⠘⣧⠀⠀⠀⠀⠀⢰⣷⣹⠀⠙⣿⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠈⣷⣝⣿⣿⣷⣄⠀⠀⠈⢇⠸⡄⠈⣇⠀⠀⢻⣆⠀⠘⣇⠀⠀⣠⣾⣽⢹⡟⠀⢰⣷⡄⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢻⣾⢻⠙⢿⣿⡇⠀⠀⠈⢧⢳⠀⢸⡀⠀⠀⢻⣆⠀⢻⡄⢠⣿⣯⣽⣓⣧⣤⠾⢹⣿⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢸⣿⣼⡇⠀⠙⣿⠀⠀⠀⠈⢏⢧⠀⣇⠀⠀⠀⢻⣆⠀⢷⠘⣿⣮⡻⣿⠁⠀⢀⣯⣿⡄⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢿⣿⣧⡀⠀⠀⠀⠀⠀⠀⠘⡾⡄⢸⠀⠀⠀⠈⢻⣆⠈⢷⣷⣾⣟⣻⣶⣿⡿⠛⢿⣷⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠈⣿⣿⣿⣦⣀⠀⠀⠀⠀⠀⢳⣇⠘⡆⠀⠀⠀⠀⠻⣶⢺⡏⢹⡟⠀⠉⠁⠀⠀⠀⢩⣍⠙⡆⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠸⣟⣿⣿⣿⣧⠀⢀⣤⣤⡸⣸⠀⡇⠀⠀⠀⠀⠀⠙⣿⣷⢡⣿⣶⣄⠀⠀⣄⠀⣦⣍⠙⢳⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠹⡿⢿⡙⠿⠀⢸⡟⢲⣷⡿⡄⢿⠀⠀⠀⠀⠀⠀⠘⣏⢸⣇⣍⢻⣷⣀⢻⣦⣤⣌⡙⣦⡇⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠹⣯⢷⠀⠀⠸⡇⠀⢿⣧⡇⢸⠀⠀⠀⠀⠀⠀⠀⣼⢸⣿⣯⠀⣿⣿⣷⣝⣿⣻⣿⣼⣷⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢻⣎⣧⠀⠐⣇⠀⠘⣽⣿⡸⡆⠀⠀⠀⠀⠀⠀⠈⠋⠈⠻⣼⣿⢶⢿⣿⣯⡻⣿⣿⣾⣷⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢻⡼⡆⠀⣿⡀⠀⣿⢿⡇⢷⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠘⣿⣾⢧⠈⠙⠿⣮⠟⠉⠙⢦⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠈⢿⢻⢠⣿⡇⠀⠹⣄⢳⣜⡆⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢹⡏⠪⠳⢤⣄⣀⠀⠀⠀⠈⢣⠀⠀⠀⠀⠀⠀⠀⠀⠀
///⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠘⣎⣿⡟⡇⠀⠀⠈⢻⣿⣷⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢳⡄⠀⠀⠀⠙⢧⡀⢀⡄⠈⡇⠀⠀⠀⠀⠀⠀⠀⠀

Compilation message (stderr)

street_lamps.cpp: In function 'int main()':
street_lamps.cpp:82:13: warning: unused variable 'k' [-Wunused-variable]
   82 |   int a, b, k = 0;
      |             ^

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