#include <stdio.h>
#include <string.h>

int main()
{
        double b1, b2, b3;

        scanf("%lf %lf %lf", &b1, &b2, &b3);

        double r, d, y;

        r = (b2 - b3) / (b1 - b2);
        d = ((b2 * (b1 - b2)) - (b1 * (b2 - b3))) / (b1 - b2);


        y = b3 * r + d;

        printf("%ld\n", (int)y);

        return 0;
}