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Cowntact Tracing

Time limit1sMemory limit512 MB

Summary
Given a final set of infected cows and a time-stamped list of hoof-shake pairs, count possible patient-zero cows and the range of transmission limits K consistent with the data.
Level

Medium7 of 10

Topics
Simulation, Brute force, Implementation, Graph
Solved
No attempts yet

Problem

Farmer John is worried for the health of his cows (conveniently numbered 1…N1 \ldots N as always) after an outbreak of the highly contagious bovine disease COWVID-19.

Recently, Farmer John tested all of his cows and found some of them to be positive for the disease. Using video footage from inside his barn, he is able to review recent interactions between pairs of cows. It turns out that when cows greet each other, they shake hooves, a gesture that can unfortunately spread the infection from one cow to another. Farmer John assembles a time-stamped list of interacting pairs of cows, with entries of the form (t,x,y)(t, x, y), meaning that at time tt, cow xx shook hooves with cow yy. Farmer John also knows the following:

(i) Exactly one cow on his farm could have started out carrying the disease (we'll call this cow "patient zero").

(ii) Once a cow is infected, she passes the infection along with her next KK hoof shakes (possibly including the same partner cow several times). After shaking hooves KK times, she no longer passes the infection along with subsequent hoof shakes (since at this point she realizes she is spreading the infection and washes her hooves carefully).

(iii) Once a cow is infected, she stays infected.

Unfortunately, Farmer John doesn't know which of his NN cows is patient zero, nor does he know the value of KK! Please help him narrow down the possibilities for these unknowns based on his data. It is guaranteed that at least one possibility is valid.

Input

The first line of the input file contains NN (2≤N≤1002 \leq N \leq 100) and TT (1≤T≤2501 \leq T \leq 250). The next line contains a string of length NN whose entries are 0s and 1s, describing the current state of Farmer John's NN cows: 0 represents a healthy cow and 1 represents a cow presently with the disease. Each of the next TT lines describes a record in Farmer John's list of interactions and consists of three integers tt, xx, and yy, where tt is a positive integer time of the interaction (t≤250t \leq 250) and xx and yy are distinct integers in the range 1…N1 \ldots N, indicating which cows shook hands at time tt. At most one interaction happens at each point in time.

Output

Print a single line with three integers xx, yy, and zz, where xx is the number of possible cows who could have been patient zero, yy is the smallest possible value of KK consistent with the data, and zz is the largest possible value of KK consistent with the data (if there is no upper bound on KK that can be deduced from the data, print "Infinity" for zz). Note that it might be possible to have K=0K=0.

Hint

The only candidate for patient zero is cow 1. For all K>0K>0, cow 1 infects cow 2 at time 7, while cows 3 and 4 remain uninfected.

Examples1

  1. Example 1

    Input
    4 3
    1100
    7 1 2
    5 2 3
    6 2 4
    
    Expected output
    1 1 Infinity