20220601

#include<stdio.h>

int main()

{

int i,b,a,sum=0;

scanf("%d %d",&a,&b);

for (i=a;i<=b;i++)

{

if (i%2==0)

{

sum=sum-i;

}

else if (i%2!=0)

{

sum=sum+i;

}

}

printf("%d",sum);

return 0;

}

*/

#include<stdio.h>

int main()

{

int a,b,c,d;

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

d = b*(c-1)+a;

printf("%d",d);

}