#include<iostream>

 #include<cstring>

 #include<algorithm>

 #include<stdio.h>

 #include<cmath>

 #include<vector>

 using namespace std;

 vector<int>vv[];

 vector<int>ss[];

 int f[],N,M,W,wi[],pi[],dp[];

 int find( int x ){

     if( x != f[x] )return f[x] = find(f[x]);

     return x;

 }

 void inint( ){

     memset( dp,,sizeof(dp) );

     for( int i = ; i <= N; i++ ) f[i] = i;

     for( int i = ; i <= N; i++ )vv[i].clear();

     for( int i = ; i <= N; i++ )ss[i].clear();

     for( int j = ; j <= N; j++ )

         scanf("%d%d",&pi[j],&wi[j]);

 }

 int main( )

 {

      while( scanf("%d%d%d",&N,&W,&M) != EOF )

      {

          inint( );

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

          {

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

              u = find( u );  v = find( v );

              if( u != v )f[u] = v;

          }

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

             vv[find(i)].push_back(i);

         int k = ;

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

         {

             int len = vv[i].size();

             if( len ==  )continue; k++;

             for( int j = ; j < len; j++ )

             ss[k].push_back(vv[i][j]);

         }

         for( int i = ; i <= k; i++ )                       // 这里是分组背包；

         for( int j = W; j >= ; j-- )

         for( int t = ; t < ss[i].size( ); t++ )

         if( j >= wi[ss[i][t]] )

             dp[j] = max( dp[j],dp[j - wi[ss[i][t]]] + pi[ss[i][t]] );

         cout<<dp[W]<<endl;

      }

      return ;

 }