Write a program to calculate sum of the elements of an 2D array.

#include<iostream>
using namespace std;
int main()
{
int a[100][100];
int r,c;
cout<<"Enter no. of rows & columns: ";
cin>>r>>c;;
cout<<"Enter "<<r*c<<" values : ";
for(int i=0;i<r;i++) {
for(int j=0;j<c;j++) {
cin>>a[i][j];
}
}
for(int i=0;i<r;i++) {
for(int j=0;j<c;j++) {
a[i][c]+=a[i][j];
}

}
for(int i=0;i<r;i++) {
for(int j=0;j<c+1;j++) {
a[r][j]+=a[i][j];
}

}
cout<<"SUM : "<<"\n";
for(int i=0;i<r+1;i++) {
for(int j=0;j<c+1;j++) {
cout<<a[i][j]<<" ";
}
cout<<"\n";
}
}