#[allow(unused_macros)]
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        let mut next = || { iter.next().unwrap() };
        input_inner!{next, $($r)*}
    };
    ($($r:tt)*) => {
        let stdin = std::io::stdin();
        let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock()));
        let mut next = move || -> String{
            bytes
                .by_ref()
                .map(|r|r.unwrap() as char)
                .skip_while(|c|c.is_whitespace())
                .take_while(|c|!c.is_whitespace())
                .collect()
        };
        input_inner!{next, $($r)*}
    };
}

#[allow(unused_macros)]
macro_rules! input_inner {
    ($next:expr) => {};
    ($next:expr, ) => {};

    ($next:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($next, $t);
        input_inner!{$next $($r)*}
    };

    ($next:expr, mut $var:ident : $t:tt $($r:tt)*) => {
        let mut $var = read_value!($next, $t);
        input_inner!{$next $($r)*}
    };
}

#[allow(unused_macros)]
macro_rules! read_value {
    ($next:expr, ( $($t:tt),* )) => {
        ( $(read_value!($next, $t)),* )
    };

    ($next:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
    };

    ($next:expr, [ $t:tt ]) => {
        {
            let len = read_value!($next, usize);
            (0..len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
        }
    };

    ($next:expr, chars) => {
        read_value!($next, String).chars().collect::<Vec<char>>()
    };

    ($next:expr, bytes) => {
        read_value!($next, String).into_bytes()
    };

    ($next:expr, usize1) => {
        read_value!($next, usize) - 1
    };

    ($next:expr, $t:ty) => {
        $next().parse::<$t>().expect("Parse error")
    };
}
//usage
//input! {
//  h: i32;
//  v: [i32; n]
//  x: [[i32; n]; m]
//  f: chars <- Vec<char>
//}

struct Graph {
    num_node: usize,
    edges: Vec<(usize, usize, i64)>,
}

impl Graph {
    fn new(num_of_node: usize) -> Self {
        Graph { num_node: num_of_node, edges: Vec::new() }
    }

    fn add_edge(&mut self, start_node: usize, end_node: usize, edge_cost: i64, directed: bool) -> () {
        self.edges.push((start_node, end_node, edge_cost));
        if !directed { self.edges.push((end_node, start_node, edge_cost)); }
    }

    fn bellman_ford(&self, start_node: usize) -> i64 {
        let node = self.num_node;
        let mut distance: Vec<i64> = vec![1000000000007; node];
        distance[start_node] = 0;
        for i in 0..node {
            for &(u, v, c) in &self.edges {
                if distance[u] != 1000000000007 && distance[u] + c < distance[v] {
                    distance[v] = distance[u] + c;
                    if i == (node - 1) && v == (node - 1) {
                        return -1000000000007;
                    }
                }
            }
        }
        -distance[node - 1]
    }
}


fn main() {
    input! {
        n: usize,
        m: usize,
        edges: [(usize, usize, i64); m]
    }
    let mut graph = Graph::new(n);
    for i in &edges {
        graph.add_edge(i.0 - 1, i.1 - 1, i.2 * (-1), true);
    }
    let ans = graph.bellman_ford(0);
    if ans == -1000000000007 {
        println!("inf");
    } else {
        println!("{}", ans);
    }
}



Measured memory_bytes: 4352