#include <stdio.h>
void change_even_odd(int size, int a[]) {
int count = 0;
for(int i = 0; i < size; i++) {
if (a[i] %2 == 0) {
count++;
}
}
int b[size], cymma=0;
if (count > 5) {
for(int i = 0; i < size; i++) {
if (a[i] %2 == 0) {
b[i] = a[i];
} else {
while(a[i] != 0) {
cymma += a[i]%10;
a[i]/=10;
}
b[i] = cymma;
}
}
} else {
for(int i = 0; i < size; i++) {
if (a[i] %2 == 0) {
while(a[i] != 0) {
cymma += a[i]%10;
a[i]/=10;
}
b[i] = cymma;
} else {
b[i] = a[i];
}
}
}
for(int i = 0; i < size; i++) {
a[i] = b[i];
}
}
int main() {
int size;
scanf("%d", &size);
int a[size][size];
for(int i = 0;i < size; i++) {
for(int j = 0; j < size; j++) {
scanf("%d", &a[i][j]);
}
}
printf("%lf",diagonal_average(size, a));
return 0;
}