#include<bits/stdc++.h>

using namespace std;

#define Fopen freopen("_in.txt","r",stdin); freopen("_out.txt","w",stdout);

#define LL long long

#define ULL unsigned LL

#define fi first

#define se second

#define pb push_back

#define lson l,m,rt<<1

#define rson m+1,r,rt<<1|1

#define lch(x) tr[x].son[0]

#define rch(x) tr[x].son[1]

#define max3(a,b,c) max(a,max(b,c))

#define min3(a,b,c) min(a,min(b,c))

typedef pair<int,int> pll;

const int inf = 0x3f3f3f3f;

const int _inf = 0xc0c0c0c0;

const LL INF = 0x3f3f3f3f3f3f3f3f;

const LL _INF = 0xc0c0c0c0c0c0c0c0;

const LL mod =  (int)1e9+;

const int N = 1e5 + ;

const int M = 1e6 + ;

int head[N], to[M], nt[M], tot = ;

int a[N];

vector<int> vc[N];

void add(int u, int v){

    to[tot] = v;

    nt[tot] = head[u];

    head[u] = tot++;

}

int n, m, u, v, op;

int belong[N], dfn[N], low[N], now_time, scc_cnt;

int mx[N], mn[N], ret[N];

stack<int> s;

void dfs(int u){

    dfn[u] = low[u] = ++now_time;

    s.push(u);

    for(int i = head[u]; ~i; i = nt[i]){

        if(!dfn[to[i]]) dfs(to[i]);

        if(!belong[to[i]]) low[u] = min(low[u], low[to[i]]);

    }

    if(dfn[u] == low[u]){

        ++scc_cnt;

        int now;

        while(){

            now = s.top(); s.pop();

            belong[now] = scc_cnt;

            if(now == u) break;

        }

    }

}

void scc(int n){

    now_time = scc_cnt = ;

    for(int i = ; i <= n; ++i)

        if(!belong[i]) dfs(i);

    int v;

    for(int i = ; i <= n; ++i){

        for(int j = head[i]; ~j; j=nt[j]){

            v = to[j];

            if(belong[v] != belong[i]){

                    vc[belong[i]].pb(belong[v]);

            }

        }

    }

    for(int i = ; i <= n; ++i){

        int rt = belong[i];

        if(ret[rt] == ){

            ret[rt] = -;

            mn[rt] = a[i];

            mx[rt] = a[i];

        }

        else {

            mn[rt] = min(mn[rt], a[i]);

            mx[rt] = max(mx[rt], a[i]);

        }

    }

}

int ans = ;

int solve(int x){

    if(ret[x] != -) return mx[x];

    ret[x] = ;

    int mmax = -;

    if(x == belong[n]) mmax = mx[x];

    for(int v : vc[x]){

        mmax = max(solve(v), mmax);

    }

    if(mmax != -) {

        mx[x] = max(mx[x], mmax);

        ans = max(ans, mx[x]-mn[x]);

    }

    else mx[x] = -;

    return mx[x];

}

int main(){

    memset(head, -, sizeof(head));

    scanf("%d%d", &n, &m);

    for(int i = ; i <= n; ++i) scanf("%d", &a[i]);

    for(int i = ; i <= m; ++i){

        scanf("%d%d%d", &u, &v, &op);

        add(u, v);

        if(op == ) add(v, u);

    }

    scc(n);

    solve(belong[]);

    cout << ans << endl;

    return ;

}