find the errors in the MATLAB codes The program runs, then stops and gives an error of double going into the switch

Horvector=[1209 1336 1477]; 
Vervector=[697, 770, 852, 941]; 

x=input('Enter Phone Number: ','s'); 

a=0.5; 
t=0:1/8192:0.5; 
%initialize z as a matrix
z=zeros(length(x),length(t));
for i=1:length(x) 
    y=x(i); 
    switch y 

    case '1' 
        %the ith row of z is equal to the right side
        z(i,:)=a*sin(2*pi*Horvector(1)*t) + a*sin(2*pi*Vervector(1)*t); 
    case '2' 
        z(i,:)=a*sin(2*pi*Horvector(2)*t) + a*sin(2*pi*Vervector(1)*t); 
    case '3' 
        z(i,:)=a*sin(2*pi*Horvector(3)*t) + a*sin(2*pi*Vervector(1)*t); 
    case '4' 
        z(i,:)=a*sin(2*pi*Horvector(1)*t) + a*sin(2*pi*Vervector(4)*t); 
    case '5' 
        z(i,:)=a*sin(2*pi*Horvector(2)*t) + a*sin(2*pi*Vervector(2)*t); 
    case '6' 
        z(i,:)=a*sin(2*pi*Horvector(1)*t) + a*sin(2*pi*Vervector(2)*t); 
    case '7' 
        z(i,:)=a*sin(2*pi*Horvector(1)*t) + a*sin(2*pi*Vervector(3)*t); 
    case '8' 
        z(i,:)=a*sin(2*pi*Horvector(2)*t) + a*sin(2*pi*Vervector(3)*t); 
    case '9' 
        z(i,:)=a*sin(2*pi*Horvector(3)*t) + a*sin(2*pi*Vervector(3)*t); 
    case '*' 
        z(i,:)=a*sin(2*pi*Horvector(1)*t) + a*sin(2*pi*Vervector(4)*t); 
    case '0' 
        z(i,:)=a*sin(2*pi*Horvector(2)*t) + a*sin(2*pi*Vervector(4)*t); 
    case '#' 
        z(i,:)=a*sin(2*pi*Horvector(3)*t) + a*sin(2*pi*Vervector(4)*t); 
    otherwise 
        disp('Enter a valid number or * or #') 
    end 
end 


%to listen to the tones with a 0.25 sec pause between each tone 

for i=1:length(x) 
    %play the ith row
    sound(z(i,:)); 
    pause(0.25); 
end