#include<bits/stdc++.h>

using namespace std;
using ll=long long;

// マクロの定義
#define all(x) x.begin(), x.end()
#define len(x) ll(x.size())
#define elif else if
#define unless(cond) if (!(cond))

// オーバーロードマクロ
#define overload2(_1, _2, name, ...) name
#define overload3(_1, _2, _3, name, ...) name
#define overload4(_1, _2, _3, _4, name, ...) name
#define overload5(_1, _2, _3, _4, _5, name, ...) name

// 繰り返し系
#define rep1(n) for (ll i=0; i<n; i++)
#define rep2(i,n) for (ll i=0; i<n; i++)
#define rep3(i,a,b) for (ll i=a; i<b; i++)
#define rep4(i,a,b,c) for (ll i=a; i<b; i+=c)
#define rep(...) overload4(__VA_ARGS__,rep4,rep3,rep2,rep1)(__VA_ARGS__)

#define foreach1(x,a) for (auto &&x: a)
#define foreach2(x,y,a) for (auto &&[x,y]: a)
#define foreach3(x,y,z,a) for (auto &&[x,y,z]: a)
#define foreach4(x,y,z,w,a) for (auto &&[x,y,z,w]: a)
#define foreach(...) overload5(__VA_ARGS__,foreach4,foreach3,foreach2,foreach1)(__VA_ARGS__)

// 除算に関する関数
template<typename T, typename U>
T floor(T x, U y){return (x>0 ? x/y: (x-y+1)/y);}

template<typename T, typename U>
T ceil(T x, U y){return (x>0 ? (x+y-1)/y: x/y);}

template<typename T, typename U>
T mod(T x, U y){
    T q=floor(x,y);
    return x-q*y;
}

template<typename T, typename U>
pair<T,T> divmod(T x, U y){
    T q=floor(x,y);
    return {q,x-q*y};
}

// 指数に関する関数
ll intpow(ll x, ll y){
    ll a=1;
    while (y){
        if (y&1) a*=x;
        x*=x;
        y>>=1;
    }
    return a;
}

ll modpow(ll x, ll y, ll z){
    ll a=1;
    while (y){
        if (y&1) (a*=x)%=z;
        (x*=x)%=z;
        y>>=1;
    }
    return a;
}

ll sum(vector<int> &X){
    ll y=0;
    for (auto &&x: X) y+=x;
    return y;
}

template<typename T>
T sum(vector<T> &X){
    T y=T(0);
    for (auto &&x: X) y+=x;
    return y;
}

// max, min
template<typename T, typename U>
inline bool chmax(T &a, const U b){
    return (a<b ? a=b, 1: 0);
}

template<typename T, typename U>
inline bool chmin(T &a, const U b){
    return (a>b ? a=b, 1: 0);
}

template<class... T>
constexpr auto max(T... a){
    return max(initializer_list<common_type_t<T...>>{a...});
}
template<class... T>
constexpr auto min(T... a){
    return min(initializer_list<common_type_t<T...>>{a...});
}

template<class T>
T max(vector<T> X){
    T alpha=X[0];
    for (auto x:X) chmax(alpha, x);
    return alpha;
}

template<class T>
T min(vector<T> X){
    T alpha=X[0];
    for (auto x:X) chmin(alpha, x);
    return alpha;
}

// 入出力
template<class... T>
void input(T&... a){(cin >> ... >> a);}

void print(){cout << "\n";}

template<class T, class... Ts>
void print(const T& a, const Ts&... b){
    cout << a;
    (cout << ... << (cout << " ", b));
    cout << "\n";
}

template<typename T, typename U>
istream &operator>>(istream &is, pair<T,U> &P){
    is >> P.first >> P.second;
    return is;
}

template<typename T, typename U>
ostream &operator<<(ostream &os, const pair<T,U> &P){
    os << P.first << " " << P.second;
    return os;
}

template<typename T>
vector<T> vector_input(int N, int index){
    vector<T> X(N+index);
    for (int i=index; i<index+N; i++) cin >> X[i];
    return X;
}

template<typename T>
istream &operator>>(istream &is, vector<T> &X){
    for (auto &x: X) is >> x;
    return is;
}

template<typename T>
ostream &operator<<(ostream &os, const vector<T> &X){
    int N=(int)len(X);
    rep(i,N) os << (i ? " ": "") << X[i];
    return os;
}

template<typename A>
struct Extended_Algebra{
    private:
    A val; int inf;

    public:
    Extended_Algebra(): Extended_Algebra(0,0){}
    Extended_Algebra(A val): Extended_Algebra(val,0){}
    Extended_Algebra(A val, int inf): val(val), inf(inf>0? 1:(inf<0?-1:0)){}

    // マイナス元
    Extended_Algebra operator-() const { return Extended_Algebra(-val, -inf);}

    // 正の元?
    bool is_positive(bool zero=true) const {
        if (inf==1) return true;
        if (inf==-1) return false;
        if (zero) return val>=0;
        return val>0;
    }

    // 負の元?
    bool is_negative(bool zero=true) const {
        if (inf==-1) return true;
        if (inf==1) return false;
        if (zero) return val<=0;
        return val<0;
    }

    // 0 ?
    inline bool is_zero() const {return inf==0 && val==0;}

    // 有界?
    inline bool is_bounded() const {return inf==0;}

    // 加法
    Extended_Algebra& operator+=(const Extended_Algebra &y){
        assert (!((inf==1 && y.inf==-1)||(inf==-1 && y.inf==1)));

        if (inf==0 && y.inf==0){
            val+=y.val;
        }else if(inf==1 || y.inf==1){
            inf=1;
        }else{
            inf=-1;
        }

        return *this;
    }

    friend Extended_Algebra operator+(const Extended_Algebra &x, const Extended_Algebra &y) {return Extended_Algebra(x)+=y;}

    // 減法
    Extended_Algebra& operator-=(const Extended_Algebra &y){
        assert (!((inf==1 && y.inf==1)||(inf==-1 && y.inf==-1)));

        if (inf==0 && y.inf==0){
            val-=y.val;
        }else if(inf==1 || y.inf==-1){
            inf=1;
        }else{
            inf=-1;
        }

        return *this;
    }

    friend Extended_Algebra operator-(const Extended_Algebra &x, const Extended_Algebra &y) {return Extended_Algebra(x)-=y;}

    // 乗法
    Extended_Algebra& operator*=(const Extended_Algebra &y){
        if (is_zero() || y.is_zero()){
            val=0; inf=0;
        }else{
            if (is_bounded() && y.is_bounded()){
                val*=y.val;
            }
            else if (!(is_positive() ^ y.is_positive())) {inf=1;}
            else {inf=-1;}
        }
        return *this;
    }

    friend Extended_Algebra operator*(const Extended_Algebra &x, const Extended_Algebra &y) {return Extended_Algebra(x)*=y;}

    // 除法
    Extended_Algebra& operator/=(const Extended_Algebra &y){
        assert (is_bounded() || y.is_bounded());
        assert (!y.is_zero());

        if (is_bounded()){
            if (y.is_bounded()) val/=y.val;
            else val=0;
        }else if (y.is_negative()){
            inf=-inf;
        }
        return *this;
    }

    friend Extended_Algebra operator/(const Extended_Algebra &x, const Extended_Algebra &y) {return Extended_Algebra(x)/=y;}

    // 比較
    friend bool operator==(const Extended_Algebra &x, const Extended_Algebra &y) {
        if (x.inf!=0) return x.inf==y.inf;
        return (y.inf==0) && x.val==y.val;
    }

    friend bool operator<(const Extended_Algebra &x, const Extended_Algebra &y){
        if (x.inf==1) return false;
        if (x.inf==0) return (y.inf==1) || (y.inf==0 && x.val<y.val);
        return y.inf>=0;
    }

    friend bool operator!=(const Extended_Algebra &x, const Extended_Algebra &y) {return !(x==y);}
    friend bool operator> (const Extended_Algebra &x, const Extended_Algebra &y) {return y<x;}
    friend bool operator<=(const Extended_Algebra &x, const Extended_Algebra &y) {return (x<y) || (x==y);}
    friend bool operator>=(const Extended_Algebra &x, const Extended_Algebra &y) {return (x>y) || (x==y);}

    // 入力
    friend istream &operator>>(istream &is, Extended_Algebra &x) {
        is >> x.val;
        return (is);
    }

    // 出力
    friend ostream &operator<<(ostream &os, const Extended_Algebra &x) {
        if (x.inf==1) {return cout << "inf";}
        if (x.inf==-1) {return cout << "-inf";}
        return os << x.val;
    }
};

// 無限大の元
template<typename A>
Extended_Algebra<A> infinity(){return Extended_Algebra<A>(A(),1);}

using T=Extended_Algebra<ll>;

int main(){
    int N,M; input(N,M);
    vector<T> H=vector_input<T>(N,1);

    vector<vector<int>> S(N+1);
    int x,y;
    rep(M){
        input(x,y);
        S[x].emplace_back(y);
        S[y].emplace_back(x);
    }

    T inf=infinity<ll>();

    // チェリーちゃん
    vector<vector<T>> DP_c(N+1, {-inf,-inf});
    DP_c[1][0]=0;

    rep(a,1,N+1){
        foreach(b,S[a]){
            if (a<b){
                if (H[a]<H[b]) chmax(DP_c[b][1], DP_c[a][0]+(H[b]-H[a]));
                else chmax(DP_c[b][0], max(DP_c[a]));
            }
        }
    }

    // ゼルコバ君
    vector<vector<T>> DP_z(N+1, {-inf,-inf});
    DP_z[N][0]=0;

    for (int a=N; a>=1; a--){
        foreach(b,S[a]){
            if (a>b){
                if (H[a]<H[b]) chmax(DP_z[b][1], DP_z[a][0]+(H[b]-H[a]));
                else chmax(DP_z[b][0], max(DP_z[a]));
            }
        }
    }

    print((max(DP_c[N])>-inf) ? max(DP_c[N]): -1);
    print((max(DP_z[1])>-inf) ? max(DP_z[1]): -1);
}