Area triangle in C language

#include <stdio.h>

void main()
{
    float a,b,c;
    float p,area,s;

    a=5;
    b=5;
    c=6;

    s =((a+b+c)/2);
    p = (s*(s-a)*(s-b)*(s-c));
    area = pow(p,.5);
    printf("area is %f", area);

}