Here is what is in the file:
x1=input('enter value for x1 : ');
x2=input('enter value for x2 : ');
n1=input('enter time interval n1 : ');
n2=input('enter time interval n2 : ');
subplot(2,2,1);
stem(n1,x1);
title('signal1')
subplot(2,2,2);
stem(n2,x2);
title('signal2')
sigadd(x1,n1,x2,n2)