//#pragma comment(linker, "/STACK:102400000, 102400000")

 #include <algorithm>

 #include <iostream>

 #include <cstdlib>

 #include <cstring>

 #include <cstdio>

 #include <vector>

 #include <cmath>

 #include <ctime>

 #include <list>

 #include <set>

 #include <map>

 using namespace std;

 typedef long long LL;

 typedef pair <int, int> P;

 const int N = 1e5 + ;

 struct Edge {

     int next, to;

 }edge[N];

 int head[N], tot, in[N];

 LL a[N], b[N], ans, d[N], mod = 1e9 + ; //d[i]表示b[i.son]*count[i,j]+b[i]

 bool vis[N];

 void init(int n) {

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

         head[i] = -;

         in[i] = ;

         vis[i] = false;

     }

     tot = ;

     ans = ;

 }

 inline void add_edge(int u, int v) {

     edge[tot].next = head[u];

     edge[tot].to = v;

     head[u] = tot++;

 }

 void dfs(int u) {

     d[u] = b[u] % mod;

     for(int i = head[u]; ~i; i = edge[i].next) {

         int v = edge[i].to;

         if(!vis[v]) { //说明这个点以及子树没访问

             dfs(v);

             vis[v] = true;

         }

         ans = (ans + a[u] * d[v] % mod) % mod;

         d[u] = (d[v] + d[u]) % mod;

     }

 }

 int main()

 {

     int n, m, u, v;

     while(scanf("%d %d", &n, &m) != EOF) {

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

             scanf("%lld %lld", a + i, b + i);

         }

         init(n);

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

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

             add_edge(u, v);

             ++in[v];

         }

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

             if(!in[i]) { //入度为0

                 dfs(i);

             }

         }

         printf("%lld\n", ans);

     }

     return ;

 }