#include <iostream>
#include <vector>
#include <queue>
#include <cstring>
using namespace std;
int main() {
    int h1, m1, h2, m2;
    cin >> h1 >> m1;
    cin >> h2 >> m2;

    int di[] = {-1, 1, 0, 0};
    int dj[] = {0, 0, -1, 1};
    bool visited[24][60];
    memset(visited, false, sizeof visited);
    visited[h1][m1] = true;
    queue<int> q;
    q.push(h1);
    q.push(m1);
    q.push(0);

    while(!q.empty()) {
        int ch = q.front();
        q.pop();
        int cm = q.front();
        q.pop();
        int buttons_clicked = q.front();
        q.pop();
        if(ch == h2 and cm == m2) {
            cout << buttons_clicked << endl;
            return 0;
        }
        for(int k = 0; k < 4; k++) {
            int th = ch + di[k];
            int tm = cm + dj[k];

            if(tm == 60) {
                tm = 0;
                th++;
            }
            if(tm == -1) {
                tm = 59;
                th--;
            }
            if(th == 24) {
                th = 0;
            }
            if(th == -1) {
                th = 23;
            }
            if(!visited[th][tm]) {
                visited[th][tm] = true;
                q.push(th);
                q.push(tm);
                q.push(buttons_clicked + 1);
            }
        }
    }

    return 0;
}

// 00:00 - 23:59
// 00:00 --> 00:59