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#include <iostream>
#include <stack>
using namespace std;

void update(short int mapa[300][300], short int maksy[300], short int what, int n, int newval, short int maks[1])
{ 
  short int i, j;

  if(newval < maksy[what]) return;
  maksy[what] = newval;
  if(maks[0]<newval) maks[0] = newval;
  for(i = 0; i < n; ++i){
    if(mapa[what][i] > 1){
	mapa[what][i] = newval + 1;
	update(mapa, maksy, what, n, newval + 1, maks);
    }
  } 
}

void prepare(short int mapa[300][300], short int maksy[300], int n, int a1 = -1, int a2 = -1, int a3 = -1, int a4 = -1){
    int i,j;
    for(i=0;i<n;++i) maksy[i]=0;
    for(i=0; i<n; ++i){
	for(j=i; j<n;++j){
	    if((j==i) && (j != a1) && (j != a2) && (j != a3) && (j != a4)){
		mapa[i][j] = 1;
		maksy[j] = 1;
	    } else {
		mapa[i][j] = 0;
	    }
	}
    }
}

int main()
{
  int n, m, k, i, j, x, y, a1, a2, a3, a4;
  short int tabl [300][300];
  short int maksy[300];
  short int kraw[400][2];
  short int maks[1];
  short int mini=300;
  long result = 0;
  bool samo = false;
  unsigned long long l, tmp, lastl = 0;
  
  cin >> n; // 1-300
  cin >> m; // 0-400
  cin >> k; // 0-min(4,m)
  maks[0] = 0;
  for(i=0; i<300; ++i){
    for(j=0; j<300; j++){
      tabl[i][j] = 0;
    }
    if(i<n){
	tabl[i][i] = 1;
	maksy[i] = 1;
    }
  }
  
  // skrajne przypadki
  if(k >= n){
    cout << "0";
    return 0;
  }
  if(k == (n-1)){
    cout << "1";
    return 0;
  }

  for(i=0; i < m; ++i){
    cin >> x;
    cin >> y;
    kraw[i][0] = x-1;
    kraw[i][1] = y-1;
    tabl[x-1][y-1] = maksy[x-1] + 1;
    update(tabl, maksy, y-1, n, maksy[x-1] + 1, maks);
  }
  mini = maks[0];
  if(k==0){
    cout << mini;
    return 0;
  }

  for(a1=0; a1<n; ++a1){
    if(k>1){
	for(a2=a1+1; a2<n;++a2){
	    if(k>2){
		for(a3=a2+1; a3<n; ++a3){
		    if(k>3){
			for(a4=a3+1; a4<n; ++a4){
    			    prepare(tabl, maksy, n, a1, a2, a3, a4);
			    maks[0] = 1;
				for(i=0; i < m; ++i){
				    if((kraw[i][0]!=a1) && (kraw[i][1]!=a1) && (kraw[i][0]!=a2) && (kraw[i][1]!=a2) && (kraw[i][0]!=a3) && (kraw[i][1]!=a3) && (kraw[i][0]!=a4) && (kraw[i][1]!=a4) ){
					tabl[kraw[i][0]][kraw[i][1]] = maksy[kraw[i][0]] + 1;
					update(tabl, maksy, kraw[i][1], n, maksy[kraw[i][0]]+1, maks);
				    }
				}
			    if(mini>maks[0]){
				mini=maks[0];
			    }
			}
		    } else {
    			prepare(tabl, maksy, n, a1, a2, a3, -1);
			maks[0] = 1;
			for(i=0; i < m; ++i){
			    if((kraw[i][0]!=a1) && (kraw[i][1]!=a1) && (kraw[i][0]!=a2) && (kraw[i][1]!=a2) &&  (kraw[i][0]!=a3) && (kraw[i][1]!=a3) ){
				tabl[kraw[i][0]][kraw[i][1]] = maksy[kraw[i][0]] + 1;
				update(tabl, maksy, kraw[i][1], n, maksy[kraw[i][0]]+1, maks);
			    }
			}
			if(mini>maks[0]){
			    mini=maks[0];
			}
		    }
		}
	    } else {
		prepare(tabl, maksy, n, a1, a2, -1, -1);
		maks[0] = 1;
		for(i=0; i < m; ++i){
		    if((kraw[i][0]!=a1) && (kraw[i][1]!=a1) && (kraw[i][0]!=a2) && (kraw[i][1]!=a2) ){
			tabl[kraw[i][0]][kraw[i][1]] = maksy[kraw[i][0]] + 1;
			update(tabl, maksy, kraw[i][1], n, maksy[kraw[i][0]]+1, maks);
		    }
		}
		if(mini>maks[0]){
		    mini=maks[0];
		}
	    }
	}
    } else {
	prepare(tabl, maksy, n, a1, -1, -1, -1);

	maks[0] = 1;
	for(i=0; i < m; ++i){
	    if((kraw[i][0]!=a1) && (kraw[i][1]!=a1)){
		tabl[kraw[i][0]][kraw[i][1]] = maksy[kraw[i][0]] + 1;
		update(tabl, maksy, kraw[i][1], n, maksy[kraw[i][0]]+1, maks);
	    }
	}
	if(mini>maks[0]){
	    mini=maks[0];
	}
    }
  }
  cout << mini;
  return 0;
}