use proconio::input;
use ac_library::MfGraph;

fn main(){
    input!{
        n: usize,
        m: usize,
        a: [(i32, i32); n],
        e: [(usize, usize, i32); m],
    }

    let mut f = MfGraph::<i32>::new(n+2);
    let s = n;
    let t = n+1;
    let mut sm = 0;
    for i in 0..n{
        f.add_edge(s, i, a[i].0);
        f.add_edge(i, t, a[i].1);
        sm += a[i].0+a[i].1;
    }
    for (u, v, c) in e{
        f.add_edge(u-1, v-1, c);
        f.add_edge(v-1, u-1, c);
        // sm += c;
    }

    let ans = sm-f.flow(s, t);
    println!("{}", ans);
    // println!("{}", f.flow(s, t));
}