#include<stdio.h>
#include<string.h>
int stack[200]={};
int top=-1;
void push(data)
{
top++;
stack[top]=data;
}
void pop()
{
if (top!=-1){
top--;
}
}
int main()
{
char str[200]={};
int sum=0, i, c, c2;
gets (str);
for (i=0; str[i]!=NULL; i++){
if (str[i]>47&&str[i]<58){
sum=0;
for (;;i++){
if(str[i]<48||str[i]>57){
break;
}
sum=sum*10+(str[i]-'0');
}
push(sum);
}
if (str[i]=='+'||str[i]=='*'||str[i]=='-'){
c=stack[top];
pop();
c2=stack[top];
pop();
switch(str[i]){
case '+':
push(c+c2);
break;
case '-':
push(c-c2);
break;
case '*':
push(c*c2);
break;
}
}
}
printf("%d", stack[top]);
}