General - Help with a course assigment-matrices

Hello, my course assigment is:
Given the 2-dimensional arrays (matrices) X and Y

a) if X,Y are both of size M by M, swap each even row of X with the column in Y of the same number.

b)if X,Y are both of size M by N, compute the matrx Zo=X+Y

c) if X is M by N and Y is N by P, compute Q=M*N

I would be glad if someone can help me.

We work with Microsoft visual C++. I have started a) but I don`t know how to swap the even rows/colums.Here is what I have done so far.
#include<iostream.h>
#include<math.h>
double X[50][50];
double Y[50][50];
double Z[50][50];
int M,N,P,Q,S,k,i,j;

main () {
cout<<"Broi redove i stulbove v matr.X=";
cin>>M;


for (i=0;i<M;i++)
for (j=0;j<M;j++) { if (i%2==0){
cout<<"X["<<i<<"]["<<j<<"]=";
cin>>X[i][j];}
}


for (i=0;i<M;i++)
for (j=0;j<M;j++) {if (j%2==0){
cout<<"Y["<<i<<"]["<<j<<"]=";
cin>>Y[i][j];}}



return 0;
}

In C++ language