#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int main() {
    int m, n;
    cin >> m >> n;
    
    vector<int> apples;
    
    // 读取苹果林矩阵并将所有苹果数存入vector
    for (int i = 0; i < m; ++i) {
        for (int j = 0; j < n; ++j) {
            int current;
            cin >> current;
            apples.push_back(current);
        }
    }
    
    // 计算vector中的最大值和最小值
    int max_apples = *max_element(apples.begin(), apples.end());
    int min_apples = *min_element(apples.begin(), apples.end());
    
    // 输出差值
    cout << max_apples - min_apples << endl;
    
    return 0;
}


/**************************************************************
	Problem: 1272
	User: fuyijun
	Language: C++
	Result: Accepted
	Time:9 ms
	Memory:2072 kb
****************************************************************/