#include <iostream>
using namespace std;
int minimumSteps(int n, int m, int x, int y) {
int totalSteps = (n - 1) / y + (m - 1) / x;
if ((n - 1) % y) {
++totalSteps;
}
if ((m - 1) % x) {
++totalSteps;
}
return totalSteps;
}
int main() {
int n, m, x, y;
cin >> n >> m;
cin >> x >> y;
cout << minimumSteps(n, m, x, y);
return 0;
}
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