include <bits/stdc++.h>

using namespace std;

double a, b, c, ans;

void scan () {

scanf ("%lf %lf %lf", &a, &b, &c);

}

void operation () {

ans = a - b * c;

}

void print () {

printf ("%.2lf", ans);

}

int main () {

scan ();
operation ();
print ();
return 0;

}