#include <bits/stdc++.h>
using namespace std;
int main(){
  int N, M;
  long long T;
  cin >> N >> M >> T;
  vector<vector<int>> E(N);
  for (int i = 0; i < M; i++){
    int a, b;
    cin >> a >> b;
    E[a].push_back(b);
  }
  vector<vector<bool>> dp(30001, vector<bool>(N, false));
  dp[0][0] = true;
  vector<vector<int>> p(N);
  for (int i = 0; i < 30000; i++){
    for (int j = 0; j < N; j++){
      if (dp[i][j]){
        p[j].push_back(i);
        for (int k : E[j]){
          dp[i + 1][k] = true;
        }
      }
    }
  }
  int ans = 0;
  if (T <= 30000){
    for (int i = 0; i < N; i++){
      if (dp[T][i]){
        ans++;
      }
    }    
  } else {
    for (int i = 0; i < N; i++){
      if (p[i].size() >= 2){
        int a = p[i][p[i].size() - 2];
        int b = p[i][p[i].size() - 1];
        int d = b - a;
        if (b + d >= 30000){
          if (T % d == a % d){
            ans++;
          }
        }
      }
    }
  }
  cout << ans << endl;
}