unordered_map<int, unordered_map<int, int>> grid;

int dx[4] = {-1, 0, 1, 0};

int dy[4] = {0, 1, 0, -1};

int x = 0, y = 0;

int dir = 0;

void setback(Robot& robot) {

robot.turnRight();

robot.turnRight();

robot.move();

robot.turnRight();

robot.turnRight();

}

void cleanRoom(Robot& robot) {

if(grid[x][y] == 1) {

return;

}

robot.clean();

grid[x][y] = 1;

for (int i = 0; i < sizeof(dx) / sizeof(dx[0]); i++) {

if (robot.move()) {

x += dx[dir];

y += dy[dir];

cleanRoom(robot);

setback(robot);

x -= dx[dir];

y -= dy[dir];

}

robot.turnRight();

dir = (dir + 1) % 4;

}

}