swimmingpool.cpp

// NOTE: it is recommended to use this even if you don't understand the following code.

#include <iostream>
#include <fstream>

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;
    cin >> N;
    
    long long P[N], media=0;
    P[0] = 0;
    
    for(long long i=0; i<N; i++) {
    	cin >> P[i];
    }

    // insert your code here
	long long pos, D = 1000000000;
	
	if (N != 2) {
		for (int i=1; i<N-1; i++) {
			if ((P[i]-P[0]) > (P[N-1]-P[i])) {
				pos = P[i] - P[0];
			} else {
				pos = P[N-1] - P[i];
			}
			
			if (pos < D) {
				D = pos;
			}
		}
	} else {
		D = P[1] - P[0];
	}
		
    cout << D << endl;; // print the result
    return 0;
}