#include<stdio.h>
#include<stdlib.h>
#include<string.h>
void push(int x);
int pop();

int top;
int S[1000];

int main(){
int x,y;
top = 0;
char s[100];

 while(scanf("%s", s) != EOF){
if(s[0] == '+' ){
x = pop();
y = pop();
 push(x + y);
}else if(s[0] == '-' ){
y = pop();
x = pop();
 push(x - y);
}else if(s[0] == '*' ){
x = pop();
y = pop();
 push(x * y);
}
else{
push(atoi(s));
}}
 
printf("%d\n", pop());
 
return 0;
} 

void push(int x){
  top++;
  S[top] = x;
}

int pop(){
top--;
return S[top+1];
}

