Please tell me, what's the problem in this code? 3/4 test cases are getting passed

#1 
#include <iostream>
#define size 10

int main() {
    int M = 0, N = 0, arr[size][size];
    std::cin >> M >> N;
    for (int i = 0; i < M; ++i)
        for (int j = 0; j < N; ++j) std::cin >> arr[i][j];
    int start_row = 0, end_row = M - 1, start_col = 0, end_col = N - 1;
    while (start_row <= end_row && start_col <= end_col) {
        for (int i = start_row; i <= end_row; ++i)
            if (start_col < end_col) std::cout << arr[i][start_col] << ", ";
        start_col++;
        for (int i = start_col; i <= end_col; ++i)
            if (start_row < end_row) std::cout << arr[end_row][i] << ", ";
        end_row--;
        for (int i = end_row; i >= start_row; --i)
            std::cout << arr[i][end_col] << ", ";
        end_col--;
        for (int i = end_col; i >= start_col; --i)
            std::cout << arr[start_row][i] << ", ";
        start_row++;
    }
    std::cout << "END";
    return 0;
}
#2

if (start_col <= end_col)// <= here in condn

if (start_row <= end_row) // <= here in condn

#3

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