fid = fopen('input.txt');
x   = [];
while 1
    tline = fgetl(fid);
    if ~ischar(tline), break, end
    x = [x;str2double(strsplit(tline,{',',' -> '}))];
end
fclose(fid);

M = zeros(max(max(x))+1);
for i=1:size(x,1)
    [r1,c1,r2,c2] = deal(x(i,2),x(i,1),x(i,4),x(i,3));
    if r1==r2 || c1==c2
        for r = min(r1,r2):max(r1,r2)
            for c=min(c1,c2):max(c1,c2)
                M(r+1,c+1)=M(r+1,c+1)+1;
            end
        end
    else
        for k = 0:abs(r1-r2)
            r = r1+sign(r2-r1)*k;
            c = c1+sign(c2-c1)*k;
            M(r+1,c+1)=M(r+1,c+1)+1;
        end
    end
end
disp(sum(sum(M>1)))