#include <stdio.h>

int main(void)
{
    double b1,b2,b3;
    scanf("%lf%lf%lf",&b1,&b2,&b3);
    printf("%ld",(long)((b2-b3)/(b1-b2)*b3+b2-b1*(b2-b3)/(b1-b2)));
    return 0;
}