C Program to check if a given matrix is a magic square matrix or not.

magic_square.c

#include <stdio.h>
void main() {
	int A[50][50];
	int i, j, M, N;
	int size;
	int rowsum, columnsum, diagonalsum;
	int magic = 0;
	
	printf("Enter the order of the matrix:\n");
	scanf("%d %d", &M, &N);
	if(M==N) {
		printf("Enter the elements of matrix \n");
		for(i=0; i<M; i++) {
			for(j=0; j<N; j++) {
				scanf("%d", &A[i][j]);
			}
		}
		
		printf("\n\nMATRIX  is\n");
		for(i=0; i<M; i++) {
			for(j=0; j<N; j++) {
				printf("%3d\t", A[i][j]);
			}
			printf("\n");
		}
		
		// calculate diagonal sum 
		diagonalsum = 0;
		for(i=0; i<M; i++) {
			for(j=0; j<N; j++) {
				if(i==j) {
					diagonalsum = diagonalsum + A[i][j];
				}
			}
		}
		
		// calculate row sum
		for(i=0; i<M; i++) {
			rowsum = 0;
			for(j=0; j<N; j++) {
				rowsum = rowsum + A[i][j];
			}
			if(rowsum != diagonalsum) {
				printf("\nGiven matrix is not a magic square");
				return;
			}
		}
		
		// calculate column sum
		for(i=0; i<M; i++) {
			columnsum = 0;
			for(j=0; j<N; j++) {
				columnsum =  columnsum + A[j][i];
			}
			if(columnsum != diagonalsum) {
				printf("\nGiven matrix is not a magic square");
				return;
			}
		}

		printf("\nGiven matrix is a magic square matrix");
	} else {
		printf("\n\nPlease enter the square matrix order(m=n) \n\n");
	}
}

how we validate the same input like:
111
111
111
it must be detected as magic square