#include using namespace std; //#define int long long #define rep(i,n) for(int (i)=0;(i)<(int)(n);(i)++) #define rept(i,n) for(int (i)=0;(i)<=(int)(n);(i)++) #define reps(i,s,n) for(int (i)=(s);(i)<(int)(n);(i)++) #define repst(i,s,n) for(int (i)=(s);(i)<=(int)(n);(i)++) #define repr(i,n) for(int (i)=(n);(i)>=0;(i)--) #define each(itr,v) for(auto (itr):(v)) #define all(c) (c).begin(),(c).end() #define pb push_back #define mp(x,y) make_pair((x),(y)) #define fi first #define se second #define chmin(x,y) x=min(x,y) #define chmax(x,y) x=max(x,y) #define ln '\n' #define dbg(x) cout<<#x" = "<<(x)< vi; typedef vector vl; typedef vector > mat; typedef pair pii; typedef pair pll; const int inf = (int)1e9; const ll linf = (ll)1e18; const int mod = (int)(1e9+7); const int dx[] = {0, 1, 0, -1}; const int dy[] = {1, 0, -1, 0}; const int ddx[] = {0, 1, 1, 1, 0, -1, -1, -1}; const int ddy[] = {1, 1, 0, -1, -1, -1, 0, 1}; const double eps = 1e-10; struct oreno_initializer { oreno_initializer() { cin.tie(0); ios::sync_with_stdio(0); } } oreno_initializer; // ━━━━☆・‥…━━━☆・‥…━━━☆・‥…━━━☆・‥…━━━☆・‥…━━━☆・‥…━━━☆・‥…━━━☆・‥…━━━☆・‥… // .。.:( ^ω^)・゚+.。.:( ^ω^)・゚+.。.:( ^ω^)・゚+.。.:( ^ω^)・゚+.。.:( ^ω^)・゚+ // ・‥…━━━☆・‥…━━━☆・‥…━━━☆・‥…━━━☆・‥…━━━☆・‥…━━━☆・‥…━━━☆・‥…━━━☆・‥…━━━☆・ ll x, y, r; signed main() { /* rep(i,100) rep(j,100) { x = i, y = j; cout << x << ' ' << y << ' '; //cin >> x >> y; while (x != y && r <= 1000000) { if (x < y) swap(x, y), r++; else { ll xx = x + y, yy = x - y; x = xx, y = yy; r++; } if (abs(x) > inf || abs(y) > inf) { //cout << -1 << ln; //return 0; break; } } if (r == 1000000 || x!=y) cout << -1 << ln; else cout << r << ln; r = 0; } */ cin >> x >> y; if (x==y) r = 0; else if (y==0) r = 1; else if (x==0) r = 2; else r = -1; cout << r << ln; }