Mcm e mcd matrice c++?

[Negan]

Si, avevo dimenticato di inserire la matrice;
#include <iostream>
#include <stdlib.h>
using namespace std;
int mat[5][5],n,m,i=0,j=0;
int main()
{

int n3;
int n4;
int mcd;
int r;
int mcm;


cout<<"n";
cin>>n;
cout<<"m";
cin>>m;
for(i=0;i<n;i++)
{
for(j=0;j<m;j++)
{
cin>>mat[i][j];

}
}
for(i=0;i<n;i++)
{
for(j=0;j<m;j++)
{
if(mat[i+1][j+1]>mat[i][j])
{
r=mat[i+1][j+1];
mat[i+1][j+1]=mat[i][j];
mat[i][j]=r;
}
n3=mat[i][j];
n4=mat[i+1][j+1];

//Calcolo MCD
r = n3 % n4;
while(r!=0)
{
n3 = n4;
n4 = r;
r = n3 % n4;
}
mcd = n4;
//Calcolo mcm


mcm = (mat[i][j] * mat[i+1][j+1])/mcd;


}
}












cout<< "MCD = " << mcd << " mcm = " << mcm << endl;
system("pause");
return 0;
}