#include using namespace std; #define ll long long #define rep(i, m, n) for (ll i = m; i < n; i++) #define rrep(i, m, n) for (ll i = m - 1; i >= n; i--) #define pb(n) push_back(n) #define UE(N) N.erase(unique(N.begin(), N.end()), N.end()); #define Sort(n) sort(n.begin(), n.end()) #define Rev(n) reverse(n.begin(), n.end()) #define HOUT(S) cout << setprecision(50) << S << endl #define pint pair #define paf(L, R) pair #define mod 998244353 #define MAX 10000010 #define endl "\n" #define ALL(a) a.begin(), a.end() #define chmax(a, b) a = (((a) < (b)) ? (b) : (a)) #define chmin(a, b) a = (((a) > (b)) ? (b) : (a)) template vector make_v(size_t a) { return vector(a); } template auto make_v(size_t a, Ts... ts) { return vector(ts...))>(a, make_v(ts...)); } template typename enable_if::value != 0>::type fill_v(U& u, const V... v) { u = U(v...); } template typename enable_if::value == 0>::type fill_v(U& u, const V... v) { for (auto& e : u) fill_v(e, v...); } int main() { cin.tie(nullptr); ios::sync_with_stdio(false); ll A, B, N, M; cin >> A >> B >> N >> M; // if(A > B) cout << (A - B + N - 1) / N + B - 1 << endl; else cout << (B - A + N - 1) / M + A - 1 << endl; }