disks2.cpp

// insert brief description of the solution here
// NOTE: it is recommended to use this even if you don't understand the following code.

#include <iostream>
#include <fstream>
#include <vector>

using namespace std;

int main() {
//  uncomment the following lines if you want to read/write from files
//  ifstream cin("input.txt");
//  ofstream cout("output.txt");

    int N, T;
    cin >> N >> T;

    vector<int> A(N), B(N);
    for (int i = 0; i < N; i++) {
        cin >> A[i] >> B[i];
    }

    // insert your code here
    int ans = -1;
    for (int i=1; i<N; i++) {
    	int time = A[i] + (24-B[i-1]);
    	if (time >=T) {
    		ans = i-1;
    		break;
		}
	}

    cout << ans << endl; // print the result
    
    return 0;
}