143ewfc

#include <iostream>
#include <vector>
#include <cmath>
using namespace std;
vector<vector<int>>B1;
int lelus,it;
int main(){
    int a,b,c,d,e,f,g,h;
    e  = 0;
    cin>> h;
    vector<vector<int>>A(h);
    vector<vector<int>>A1(h);
    vector<vector<int>>B(h);
    for(int i = 0 ; i < h ; i++){
        cin>> a>>b>>c>>d;
        A[i] = {a, b, c, d};
    }
    for(int i = 0 ; i < h ; i++){
        A1[i].push_back(A[i][0]*60 + A[i][1]);
        A1[i].push_back(A[i][2]*60 + A[i][3]);
    }
    b = 0;
    a = 0;
    for(int i = 0 ; i < h ; i++){
        if(A1[i][0]==A1[i][1]){
            for(int g = 0 ; g < 1440 ; g++){
                B[i].push_back(1);
            }
        }
        if(A1[i][0]>A1[i][1]){
            for(int g = 0 ; g < 1440 ; g++){
                if(g<A1[i][1]){
                    B[i].push_back(1);
                }
                else{
                    if(g+1>A1[i][0]){
                        B[i].push_back(1);
                    }
                    else{
                        B[i].push_back(0);
                    }
                }
            }
        }
        if(A1[i][0] < A1[i][1]){
            for(int g = 0 ; g < 1440 ; g++){
                if(A1[i][0] < g+1 && A1[i][1] > g){
                    B[i].push_back(1);
                }
                else{
                    B[i].push_back(0);
                }
            }
        }

    }
    for(int g = 0 ; g < 1440 ; g++){
        if(B[0][g] == 1){
            a = 0;
            for(int i = 0 ; i < h ; i++){
                if(B[i][g] == 1){
                    a += 1;
                }
            }
            if(a == h){
                e+=1;
            }
        }
    }
    cout<<e<<endl;
    return 0;
}