use std::io::*;
use std::str::FromStr;

fn read_vec2(n: u32) -> Vec<Vec<char>> {
    let mut v2 = Vec::with_capacity(n as usize);
    use std::io::stdin;
    use std::io::BufRead;
    let stdin = stdin();
    let mut stdin = stdin.lock();
    for _ in 0..n {
        let mut s = String::new();
        stdin.read_line(&mut s).ok();
        let v = s.trim().chars().filter(|&c| c != ' ').collect();
        v2.push(v);
    }
    v2
}

fn read_vec<T: std::str::FromStr>() -> Vec<T> {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim()
        .split_whitespace()
        .map(|e| e.parse().ok().unwrap())
        .collect()
}

fn read<T: std::str::FromStr>() -> T {
    let mut s = String::new();
    std::io::stdin().read_line(&mut s).ok();
    s.trim().parse().ok().unwrap()
}

#[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>
//}
// let s: type = read();
const INF: i64 = std::i64::MAX;
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![INF; node];
        distance[start_node] = 0;
        for i in 0..node {
            for &(u, v, c) in &self.edges {
                if distance[u] != INF && distance[u] + c < distance[v] {
                    distance[v] = distance[u] + c;
                    if i == (node - 1) && v == (node - 1) {
                        return -INF;
                    }
                }
            }
        }
        -distance[node - 1]
    }
}



fn main() {
    input!{
        n: usize, m: usize,
        edge: [(usize, usize, i64); m]
    }
    let mut graph = Graph::new(n);
    for &(a, b, c) in &edge {
        graph.add_edge(a - 1, b - 1, -c, true)
    }

    let res = graph.bellman_ford(0);

    println!("{}", if res == -INF {"inf".to_owned()} else {res.to_string().to_owned()})
}

Measured memory_bytes: 4352