import time
import robot

POWER = 70

RIGHT_WHEEL_OFFSET = 5

def careful_forward(drive_time, arlo):
    start = time.time()
    end = start + drive_time
    turning = None
    while time.time() < end:
        forward_dist = arlo.read_front_ping_sensor()
        right_dist = arlo.read_right_ping_sensor()
        left_dist = arlo.read_left_ping_sensor()
        if forward_dist > 600 and all(x > 200 for x in [right_dist, left_dist]):
            print("not blocked")
            turning = None
            arlo.go_diff(POWER, POWER + RIGHT_WHEEL_OFFSET, 1, 1)
        else:
            print("blocked")
            if turning == "R" or (forward_dist > 600 and right_dist > 200 and turning is None):
                arlo.go_diff(POWER, POWER, 1, 0)
                turning = "R"
            else:
                arlo.go_diff(POWER, POWER + RIGHT_WHEEL_OFFSET, 0, 1)
                turning = "L"

        time.sleep(0.01)

def main():
    drive_time = int(input())
    arlo = robot.Robot()
    careful_forward(drive_time, arlo)

if __name__ == "__main__":
    main()