#include <stdio.h>

int main() {
    int m, n, max = -1, min = 51, i;
    scanf("%d %d", &m, &n);

    for (i = 0; i < m * n; i++) {
        int a;
        scanf("%d", &a);
        if (a > max)
            max = a;
        if (a < min)
            min = a;
    }
    printf("%d", max - min);
    

    return 0;
}