#include #include #include #include using namespace std; #define REP(i,s,e) for (i = s; i <= e; i++) #define rep(i,n) REP (i,0,(int)(n)-1) #define RREP(i,s,e) for (i = s; i >= e; i--) #define rrep(i,n) RREP (i,(int)(n)-1,0) #define INF (int)1e8 #define MOD (int)(1e9+7) typedef long long ll; ll fib[80]; int main(void) { int i, N; ll M; cin >> N >> M; N--; fib[0] = fib[1] = 1; REP (i,2,N) fib[i] = fib[i-1] + fib[i-2]; M = fib[N] - M; int ans = 0; while (M) { i = 0; while (i < N-2 && fib[i+1] <= M) i++; M -= fib[i]; fib[i] = 1e18; ans++; if (ans > N) { cout << -1 << endl; return 0; } } cout << ans << endl; return 0; }