if() is still executing even after condition fails in c program

I had written a c.I was using goto statement thus i thought it is fault of the goto statement but when use simple printf() statement and found that it was the fault of the goto but it it fault of the if statement.here is my program

#include <stdio.h>
#include <math.h>
float power(float a,float b);
int main(){//B main
char z;
float x,y;


printf("please,enter the number on which you want to raise \nand the 
number by which you want to raise othe number resplectevly:- ");
scanf("%f %f",&x,&y);

printf("%f \n",power(x,y));
fflush(stdin);
printf("do you want to enter the numbers again? y/n:- ");
scanf(" %c",&z);
if(z=='y');
{
printf("y\n");
}
}//B main 

float power(float a,float b){//B function power

float d=pow(a,b);

return d;

}//B power power

and here is the output

 linuxman@Aspire:~/c programs/a raised to b$ ./a.out
 please,enter the number on which you want to raise 
 and the number by which you want to raise othe number resplectevly:- 4 2
 16.000000 
 do you want to enter the numbers again? y/n:- n
 y
 linuxman@Aspire:~/c programs/a raised to b$

i had enterd n and even thus it prints y.why is this happening?

noob in programing