#include <bits/stdc++.h>
#define FOR(i,a,b) for(int i = (a); i < (b); ++i)
#define REP(i,n) FOR(i,0,n)
#define RREP(i,n) for(int i = (n) - 1; (i) >= 0; --i)
#define SZ(n) (int)(n).size()
#define ALL(n) (n).begin(), (n).end()
#define MOD LL(1e9 + 7)
#define INF 1000000

using namespace std;

typedef long long LL;
typedef vector<int> VI;
typedef pair<int, int> PI;

int main() {
        int x, y;
        cin >> x >> y;
        int x2, y2;
        cin >> x2 >> y2;
        int ans = abs(x - y) + min(x, y);
        if (x > x2 && x == y && x2 == y2)
                ans++;
        cout << ans << endl;
        return 0;
}