zoj 1241 Geometry Made Simple

#include<stdio.h>
#include<math.h>
int main()
{
int a,b,c,ans=0;
while(scanf("%d%d%d",&a,&b,&c)!=EOF&&(a||b||c))
{
printf("Triangle #%d\n",++ans);
if(a==0||b==0||c==0)
{
printf("Impossible.\n\n");
continue;
}
if(a==-1)
{
if(c*c-b*b>0)printf("a = %.3lf\n",sqrt(c*c-b*b));
else
printf("Impossible.\n");
}
else
if(b==-1)
{
if(c*c-a*a>0)printf("b = %.3lf\n",sqrt(c*c-a*a));
else
printf("Impossible.\n");
}
else
{
printf("c = %.3lf\n",sqrt(a*a+b*b));
}
printf("\n");

}
return 0;

}