#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <limits>
#include <ctime>
#include <cassert>
#include <map>
#include <set>
#include <iostream>
#include <memory>
#include <string>
#include <vector>
#include <algorithm>
#include <functional>
#include <sstream>
#include <stack>
#include <queue>
#include <numeric>
#include <iterator>
#include <bitset>
#include <unordered_map>
#include <unordered_set>

using namespace std;
#define FOR(i,n) for(int i = 0; i < (n); i++)
#define sz(c) ((int)c.size())
#define ten(n) ((int)1e##n)
using ll = long long;
using Pii = pair<int, int>;
using Pll = pair<ll, ll>;

template<typename ...> static inline int getchar_unlocked(void) { return getchar(); }
template<typename ...> static inline void putchar_unlocked(int c) { putchar(c); }
#define mygc(c) (c)=getchar_unlocked()
#define mypc(c) putchar_unlocked(c)
void reader(int& x) { int k, m = 0; x = 0; for (;;) { mygc(k); if (k == '-') { m = 1; break; }if ('0' <= k&&k <= '9') { x = k - '0'; break; } }for (;;) { mygc(k); if (k<'0' || k>'9')break; x = x * 10 + k - '0'; }if (m) x = -x; }
void reader(ll& x) { int k, m = 0; x = 0; for (;;) { mygc(k); if (k == '-') { m = 1; break; }if ('0' <= k&&k <= '9') { x = k - '0'; break; } }for (;;) { mygc(k); if (k<'0' || k>'9')break; x = x * 10 + k - '0'; }if (m) x = -x; }
int reader(char c[]) { int i, s = 0; for (;;) { mygc(i); if (i != ' '&&i != '\n'&&i != '\r'&&i != '\t'&&i != EOF) break; }c[s++] = i; for (;;) { mygc(i); if (i == ' ' || i == '\n' || i == '\r' || i == '\t' || i == EOF) break; c[s++] = i; }c[s] = '\0'; return s; }
int reader(string& c) { int i; for (;;) { mygc(i); if (i != ' '&&i != '\n'&&i != '\r'&&i != '\t'&&i != EOF) break; }c.push_back(i); for (;;) { mygc(i); if (i == ' ' || i == '\n' || i == '\r' || i == '\t' || i == EOF) break; c.push_back(i); }; return sz(c); }
template <class T, class S> void reader(T& x, S& y) { reader(x); reader(y); }
template <class T, class S, class U> void reader(T& x, S& y, U& z) { reader(x); reader(y); reader(z); }
template <class T, class S, class U, class V> void reader(T& x, S& y, U& z, V & w) { reader(x); reader(y); reader(z); reader(w); }
void writer(int x, char c) { int s = 0, m = 0; char f[10]; if (x<0)m = 1, x = -x; while (x)f[s++] = x % 10, x /= 10; if (!s)f[s++] = 0; if (m)mypc('-'); while (s--)mypc(f[s] + '0'); mypc(c); }
void writer(ll x, char c) { int s = 0, m = 0; char f[20]; if (x<0)m = 1, x = -x; while (x)f[s++] = x % 10, x /= 10; if (!s)f[s++] = 0; if (m)mypc('-'); while (s--)mypc(f[s] + '0'); mypc(c); }
void writer(const char c[]) { int i; for (i = 0; c[i] != '\0'; i++)mypc(c[i]); }
void writer(const string& x, char c) { int i; for (i = 0; x[i] != '\0'; i++)mypc(x[i]); mypc(c); }
void writer(const char x[], char c) { int i; for (i = 0; x[i] != '\0'; i++)mypc(x[i]); mypc(c); }
template<class T> void writerLn(T x) { writer(x, '\n'); }
template<class T, class S> void writerLn(T x, S y) { writer(x, ' '); writer(y, '\n'); }
template<class T, class S, class U> void writerLn(T x, S y, U z) { writer(x, ' '); writer(y, ' '); writer(z, '\n'); }
template<class T, class S, class U, class V> void writerLn(T x, S y, U z, V v) { writer(x, ' '); writer(y, ' '); writer(z, ' '); writer(v, '\n'); }
template<class T> void writerArr(T x[], int n) { if (!n) { mypc('\n'); return; }FOR(i, n - 1)writer(x[i], ' '); writer(x[n - 1], '\n'); }
template<class T> void writerArr(vector<T>& x) { writerArr(x.data(), (int)x.size()); }

template<class T> void chmin(T& a, const T& b) { if (a > b) a = b; }
template<class T> void chmax(T& a, const T& b) { if (a < b) a = b; }

template<class T> T gcd(T a, T b) { return b ? gcd(b, a % b) : a; }
template<class T> T lcm(T a, T b) { return a / gcd(a, b) * b; }
ll mod_pow(ll a, ll n, ll mod) {
	ll ret = 1;
	ll p = a % mod;
	while (n) {
		if (n & 1) ret = ret * p % mod;
		p = p * p % mod;
		n >>= 1;
	}
	return ret;
}
template<class T> T extgcd(T a, T b, T& x, T& y) { for (T u = y = 1, v = x = 0; a;) { T q = b / a; swap(x -= q * u, u); swap(y -= q * v, v); swap(b -= q * a, a); } return b; }
ll mod_inv(ll a, ll m) { ll x, y; extgcd<ll>(a, m, x, y); return (m + x % m) % m; }

ll a[ten(5)], b[ten(5)];
vector<int> e[ten(5)];

class UnionFind {
private:
	int n;
	vector<int> a;
public:
	UnionFind(int n) : n(n), a(n, -1) {}
	int find(int x) { return a[x] < 0 ? x : (a[x] = find(a[x])); }
	bool same(int x, int y) { return find(x) == find(y); }
	bool same(Pii& p) { return same(p.first, p.second); }
	bool unite(int x, int y) {
		x = find(x), y = find(y);
		if (x == y) return false;
		if (a[x] > a[y]) swap(x, y);
		a[x] += a[y];
		a[y] = x;
		n--;
		return true;
	}
	bool unite(Pii& p) { return unite(p.first, p.second); }
	int size() const { return n; }
	int size(int x) { return -a[find(x)]; }
};

struct P {
	ll val;
	int v;
	P() {}
	P(ll val, int v) : val(val), v(v) {}

	bool operator>(const P& r) {
		return val > r.val;
	}
};

struct Heap {
	Heap *l, *r;
	P val;
};

int __heap_pt = 0;

Heap* heapAlloc(P val) {
	static Heap buf[ten(6) * 3];

	auto& ret = buf[__heap_pt++];
	ret.l = ret.r = nullptr;
	ret.val = val;
	return &ret;
}

void clearHeap() {
	__heap_pt = 0;
}

Heap *meld(Heap *a, Heap *b) {
	if (!a) return (b);
	if (!b) return (a);

	if (a->val > b->val) swap(a, b);
	a->r = meld(a->r, b);
	swap(a->l, a->r);

	return (a);
}

void pop(Heap*& root) {
	root = meld(root->r, root->l);
}

Heap* nodes[ten(5)];
ll curB[ten(5)];

bool solve(ll sval, int n) {
	clearHeap();
	memset(curB, 0, sizeof(curB));
	FOR(i, n) {
		nodes[i] = nullptr;
		for (auto to : e[i]) {
			nodes[i] = meld(nodes[i], heapAlloc(P(a[to], to)));
		}
		curB[i] = b[i];
	}

	bool used = false;
	UnionFind uf(n);
	FOR(i, n) {
		if (uf.size(i) != 1) continue;
		if (a[i] - sval > 0) continue;
		used = true;

		while (true) {
			auto& curHeap = nodes[uf.find(i)];
			if (!curHeap) break;

			auto& bval = curB[uf.find(i)];

			P val = curHeap->val;
			if (uf.same(i, val.v)) {
				pop(curHeap);
				continue;
			}
			if (val.val - sval > bval) break;
			pop(curHeap);
			
			int vpar = uf.find(val.v);
			curHeap = meld(curHeap, nodes[vpar]);
			bval += curB[vpar];

			uf.unite(i, val.v);
			int nid = uf.find(i);
			nodes[nid] = curHeap;
			curB[nid] = bval;
		}
	}

	bool ok = used && (uf.size() == 1);
	return ok;
}

int main() {
	int n, m; reader(n, m);
	FOR(i, n) {
		reader(a[i], b[i]);
		a[i] -= b[i];
	}
	FOR(i, m) {
		int x, y; reader(x, y);
		x--; y--;
		e[x].push_back(y);
		e[y].push_back(x);
	}

	bool cur = solve(0, n);

	ll l = -1, r = ten(9) + 1;
	while (r - l != 1) {
		ll md = (l + r) / 2;
		bool ok = solve(md, n);
		if (ok) r = md;
		else l = md;
	}
	ll ans = r;
	FOR(i, n) ans += b[i];
	writerLn(ans);

	return 0;
}

Measured memory_bytes: 16252