#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const int maxn = 100010;

int n, m, l[maxn], e = 0;

int A[maxn], B[maxn], C[maxn], ind[maxn], vis[maxn];
ll val[maxn], sum[maxn];

struct Edge {
	int v, x;
} E[maxn << 1];

inline void addEdge(int u, int v) {
	E[e].v = v; E[e].x = l[u]; l[u] = e++;
}

int fa[maxn];

int getroot(int x) {
	if (x == fa[x]) return x;
	return fa[x] = getroot(fa[x]);
}

bool cmp(int x, int y) {
	return C[x] < C[y];
}

int main() {
	memset(l, -1, sizeof(l));
	scanf("%d%d", &n, &m);
	for (int i = 1; i <= n; i++) scanf("%d%d", &A[i], &B[i]);
	for (int i = 1; i <= m; i++) {
		int u, v; scanf("%d%d", &u, &v);
		addEdge(u, v); addEdge(v, u);
	}
	for (int i = 1; i <= n; i++) fa[i] = ind[i] = i, C[i] = max(A[i] - B[i], 0), sum[i] = B[i];
	sort(ind+1, ind+n+1, cmp);
	for (int _ = 1; _ <= n; _++) {
		vector<int> vec;
		int i = ind[_];
		vis[i] = 1;
		for (int p = l[i]; p >= 0; p = E[p].x) if (vis[E[p].v]) vec.push_back(getroot(E[p].v));
		sort(vec.begin(), vec.end()); vec.erase(unique(vec.begin(), vec.end()), vec.end());
		val[i] = C[i];
		for (int x = 0; x < vec.size(); x++) {
			int v = vec[x];
			// sum[v] + ? >= C[i]
			// ? >= C[i] - sum[v];
			// ? >= val[v]
			val[i] = min(val[i], max(C[i] - sum[v], val[v]));
			fa[v] = i; sum[i] += sum[v];
		}
	}
	printf("%lld\n", val[getroot(1)]+sum[getroot(1)]);
	return 0;
}