View Compilation Error

0_0_25450347_9918.cpp: In function 'int main()':
0_0_25450347_9918.cpp:8:55: error: incompatible types in assignment of 'int' to 'int [2500]'
                 a[i * n + j, k * n + (i * k + j) % n] = 1;
                                                       ^
0_0_25450347_9918.cpp:13:26: error: 'b' was not declared in this scope
             printf("%d", b[i][j]);
                          ^