#include <stdio.h>
int main()
{
    float a,b,c;
    printf("enter three sides of thw triangle:");
    scanf("%f %f %f ,&a,&b,&C");
    if (a <=0;b<=0;c=0){
        printf("invalid input");
    }
    else if ((a + b + c) || (a + c <= b) || (b + c <=a )){
        printf("invalid input\n");
    }
    else if (a == b || && b == c){
        printf("equilateral\n");
    }
    else if (a == b || b == c || a == c){
        printf("isoseceles\n");
    }
    else{
        printf("scalene\n");
    }
    return 0;
}