#include<bits/stdc++.h>
using namespace std;
typedef pair<int,int> P;
int p,r,t;
int L[333];
int lmp[333];
int tmp[333][333];
int n[333][333];
bool used[333];
int C[333];
vector<P> D;

bool isRelease( int id ){
  for(int i=0;i<r;i++)
    if( n[id][i] > L[i] ) return false;
  return true;
}

bool check(int h){

  for(int i=0;i<r;i++) L[i] = lmp[i];
  for(int i=0;i<p;i++){
    C[i] = r;
    for(int j=0;j<r;j++){
      n[i][j] = tmp[i][j];
      if( n[i][j] == 0 ) C[i]--;
    }
  }
  
  memset( used,0,sizeof( used ));
  for(int i=0;i<h;i++){
    if( L[ D[i].second ] == 0 ) return true;
    L[ D[i].second ]--;    
    n[ D[i].first ][ D[i].second ]--;
    assert( n[ D[i].first ][ D[i].second ] >= 0 );    
    if( n[ D[i].first ][ D[i].second ] == 0 ) C[ D[i].first ]--;

    if( C[ D[i].first ] == 0 ) {
      used[ D[i].first ] = true;
      for(int j=0;j<r;j++)
        L[ j ] += tmp[ D[i].first ][ j ];      
    }
  }

  /*
  cout << "time : " <<  h << endl;
  for(int i=0;i<r;i++) cout << L[i]<< " ";
  cout << endl;
  for(int i=0;i<p;i++){
    for(int j=0;j<r;j++) cout << n[i][j] << " ";
    cout << endl;
  }
  */


  bool loop = true;
  while( loop ){
    loop = false;
    for(int i=0;i<p;i++){
      if( used[i] ) continue;
      if( isRelease( i ) ) {
        for(int j=0;j<r;j++)
          L[ j ] += tmp[i][j] - n[i][j];
        used[i] = true;
        loop = true;
      }
    }
  }

  for(int i=0;i<p;i++)
    if( !used[i] ) return true;
  return false;
  
}

int main(){
  cin >> p >> r >> t;
  D.resize( t );
  for(int i=0;i<r;i++) {
    cin >> L[i]; lmp[i] = L[i];
  }
  for(int i=0;i<p;i++)
    for(int j=0;j<r;j++){
      cin >> n[i][j];
      tmp[i][j] = n[i][j];
    }
  for(int i=0;i<t;i++){
    cin >> D[i].first >> D[i].second;
    D[i].first--; D[i].second--;
  }

  int st = 0, ed = t;
  int res = -1;
  while( st <= ed ){
    int h = (st+ed)/2;
    if( check( h ) ) {
      ed = h-1; res = h;
    } else {
      st = h+1;
    }
  }
  cout << res << endl;
}