/*
#include<stdio.h>
int main()
{
int b,d =0;
char a,c;
scanf("%d",&d);
for(;;){
scanf("%c",&a);
if( a == '='){
break;
}
scanf("%d",&b);
if(a == '+'){
d = d+b;
}
else if(a == '-'){
d= d-b;
}
else if(a == '*'){
d = d*b;
}
else if(a == '/'){
d = d/b;
}
}
printf("%d",d);
return 0;
}
*/
/*
#include<stdio.h>
int main()
{
double a=0,s,e;
double b =0,c = 0,d=0;
int i;
for(i = 1; i <=5; i++)
{
scanf("%lf %lf",&s, &e);
a = e-s; //실제 일한 시간
if(a > 1)
{
if(a >5)
{
b = b+4;
}
else if( a <=5)
{
b = b+a-1;
}
}
}
//printf("%lf",b);
c= (b/0.5)*5000;
if(b >=15)
{
printf("%.0lf",c*0.95);
}
else if(b <=5)
{
printf("%0.lf",c*1.05);
}
else {
printf("%0.lf",c);
}
return 0;
}
*/
/*
#include<stdio.h>
int main()
{
int a,b,c,n,i,d=0;
scanf("%d %d %d %d",&a, &b, &c, &n);
d = d+a;
for(i = 1; i<=n-1; i++){
d = d*b+c;
}
printf("%d",d);
return 0;
}
*/
/*
#include<stdio.h>
int main()
{
int k,h,a=0,b=0,c=0,d=0;
scanf("%d %d",&k, &h);
a = k-1;
b = h-1;
for(;;){
if(k%2 != 0){
a;
}
else if(k%2 ==0){
}
else if(h%2 !=0){
}
else if(k% 2==0){
}
}
printf("%d",a+b+c+d);
return 0;
}
*/
#include<stdio.h>
int main()
{
int k,h,c=0,d=0,i;
scanf("%d %d",&k, &h);
for(i =1;i<=h;i++){
if(k%2 != 0){
c = c+k-1;
}
else if(k%2 ==0){
c = c+(k-1)*10;
}
else if(h%2 !=0){
c = c+h-1;
}
else if(h% 2==0){
c = c+(h-1)*10;
}
}
printf("%d",c);
return 0;