求助！

哪里错了？？

var x,y:array[1..100]of real;

m,n,i:longint;

c:real;

begin

read(n,M);

for i:=1 to n do

read(x[i],y[i]);

c:=m*3.1415926*2;

for i:=2 to n do

c:=c+sqrt(sqr(abs(x[i]-x))+sqr(abs(y[i]-y)));

c:=c+sqrt(sqr(abs(x[n]-x[1]))+sqr(abs(y[n]-y[1])));

write(c:0:2);

end.