ICPC2019-A game of robots.py

T = int(input())

while(T>0):
    T-=1
    inp = input()
    prevRange = 0
    dist = 55       # max dist. (=infinity) for first robot
    collision = False
    # iterate through input string
    for c in inp:
        if not(c is '.'):
            # if dist. < minDist then collision
            # where minDist = range of current point + range of prev. point
            if dist < prevRange+int(c):
                # collision
                collision = True
                break
            else:
                # no collision, make this prev. point and go on
                prevRange = int(c)
            # new point calc. dist. from here now
            dist = 0
        else:
            # no robot/point here, increment distance
            dist += 1
    # print ans.
    if collision:
        print('unsafe')
    else:
        print('safe')