#include <stdio.h>
#include <stdbool.h>

void LoadMatrixFromFile(FILE *inF, int **NNMatrix, int N) {
   for( int i = 0; i < N; i++){
     for(int j = 0; j < N; j++){
         fscanf(inF, "%d", &NNMatrix[i][j]);
         printf("%d", NNMatrix[i][j]);
     }
   }
}

bool IsElementInArea(int i, j, N){
    if ( j < N/2){
        if ((i > j + 1) && (i < N - j)){
            return true;
        }
    }
    return false;
}

int CalculateSum(FILE *outF,int **NNMatrix, int N) {
    int sum = 0;
    for (int j = 0; j < N / 2; j++) {
        for (int i = j; i < N - j; i++) {
            sum = sum + NNMatrix[i][j];
        }
    }

    printf("-------------------------");
    for (int i = 0; i < N; i++) {
        for (int j = 0; j < N; j++) {
            if (IsElementInArea(i, j, N)) {
                printf("%d", NNMatrix[i][j]);
            }
        }
    }
    printf("-------------------------");
    return sum;
}
    int main() {
        FILE *inF = fopen("input.txt", "r");
        FILE *outF = fopen("output.txt", "w");
        int N;
        fscanf(inF, "%d", &N);
        int NNMatrix[N][N];
        int (*PMatrix)[N] = NNMatrix;
        LoadMatrixFromFile(inF, &PMatrix, N);
        printf("%d",CalculateSum(outF, &PMatrix, N));
        fclose(inF);
        fclose(outF);
    }