zoj 1241 Geometry Made Simple

#include <stdio.h>#include <math.h>int main(){float a,b,c;float f;int k=1;while(scanf("%f%f%f",&a,&b,&c)&&a&&b&&c){printf("Triangle #%dn",k);if (-1==a){if (c<=b||b<=0||c<=0){printf("Impossible.");}else{f=(float)sqrt(pow(c,2)-pow(b,2));printf("a = %0.3f",f);}}if (-1==b){if (c<=a||a<=0||c<=0){printf("Impossible.");}else{f=(float)sqrt(pow(c,2)-pow(a,2));printf("b = %0.3f",f);}}if (-1==c){if (a<=0||b<=0){printf("Impossible.");}else{f=(float)sqrt(pow(a,2)+pow(b,2));printf("c = %0.3f",f);}}printf("nn");k++;}return 0;}