#include <stdio.h>
#define MAX 5
int trace(int matrix[][MAX], int order);
int main(void)
{
    int matrix[MAX][MAX], order, i, j;
    if (scanf("%d", &order) != 1 || order < 1 || order > MAX) {
        puts("Enter a square-matrix order from 1 to 5."); return 1;
    }
    for (i = 0; i < order; i++) {
        for (j = 0; j < order; j++) {
            if (scanf("%d", &matrix[i][j]) != 1 || matrix[i][j] < -20 || matrix[i][j] > 20) {
                puts("Enter matrix values from -20 to 20."); return 1;
            }
        }
    }
    printf("Trace = %d\n", trace(matrix, order));
    return 0;
}
int trace(int matrix[][MAX], int order)
{
    int i, total = 0;
    for (i = 0; i < order; i++) total += matrix[i][i];
    return total;
}