t=-2:1:2;
y=[zeros(1,2), ones(1,1), zeros(1,2)];
subplot(2,2,1);
stem(t,y);
ylabel('d(n)');
xlabel('unit impulse');

n=input('Enter n values');
t=0:1:n-1;
y1=ones(1,n);
subplot(2,2,2);
stem(t,y1);
ylabel('Amplitude');
xlabel('unit step');

n=input('Enter n values');
t=0:1:n-1;
subplot(2,2,3);
stem(t,t);
ylabel('Amplitude');
xlabel('unit ramp');

n=input('Enter length of exponential seq');
t=0:1:n-1;
a=input('Enter a value');
y2=exp(a*t);
subplot(2,2,4);
stem(t,y2);
xlabel('Exponential fun');
ylabel('Amplitude');

Output

Enter n values5
Enter n values4
Enter length of exponential seq5
Enter a value2