#include <stdio.h>

int main()
{
	int m[80][80];

	for (int i = 0; i < 80; i++) {
		for (int j = 0; j < 80; j++) {
			scanf("%d", &m[i][j]);
		}
	}

	for (int i = 1; i < 80; i++) {
		m[0][i] = m[0][i-1] + m[0][i];
	}

	for (int i = 1; i < 80; i++) {
		m[i][0] = m[i-1][0] + m[i][0];
		for (int j = 1; j < 80; j++) {
			if (m[i-1][j] < m[i][j-1])
				m[i][j] = m[i-1][j] + m[i][j];
			else
				m[i][j] = m[i][j-1] + m[i][j];
		}
	}

	printf("%d\n", m[79][79]);
}