#include<stdio.h>
int main()
{
	int a,b,c;
	scanf("%d%d%d",&a,&b,&c);
	printf("%d",a-b*c);
	return 0;
}
/**************************************************************
	Problem: 1599
	User: admin
	Language: C
	Result: Accepted
	Time:9 ms
	Memory:1144 kb
****************************************************************/