#include<bits/stdc++.h>
using namespace std;

#define REP(i,a,b) for(i=a;i<b;i++)
#define rep(i,n) REP(i,0,n)

#define mygc(c) (c)=getchar_unlocked()
#define mypc(c) putchar_unlocked(c)

#define ll long long
void reader(ll *x){int k,m=0;*x=0;for(;;){mygc(k);if(k=='-'){m=1;break;}if('0'<=k&&k<='9'){*x=k-'0';break;}}for(;;){mygc(k);if(k<'0'||k>'9')break;*x=(*x)*10+k-'0';}if(m)(*x)=-(*x);}
template <class T, class S> void reader(T *x, S *y){reader(x);reader(y);}
void writer(int x, char c){int s=0,m=0;char f[10];if(x<0)m=1,x=-x;while(x)f[s++]=x%10,x/=10;if(!s)f[s++]=0;if(m)mypc('-');while(s--)mypc(f[s]+'0');mypc(c);}
template<class T> void writerLn(T x){writer(x,'\n');}

ll N, M;
ll fib[100];

int main(){
  int i, res = 0;

  reader(&N,&M);

  fib[1] = fib[2] = 1;
  REP(i,3,N+1) fib[i] = fib[i-1] + fib[i-2];

  M = fib[N] - M;
  for(i=N-2;i;i--) if(M >= fib[i]) M -= fib[i], res++;

  if(M) res=-1;
  writerLn(res);

  return 0;
}