#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#define N 100
#define M 99

int top,S[N];
void isEmpty(void);
void push(int);
int pop(void);
void isFull(void);
int main()
{
  int a,b;
  top=0;
  char s[N];
  while(scanf("%s",s) != EOF){
    if (s[0]=='+'){
      a = pop();
      b = pop();
      push(a+b);
    }
    else if(s[0]=='-'){
      b=pop();
      a = pop();
      push(a - b);
    }
    else if(s[0]=='*'){
      a = pop();
      b = pop();
      push(a*b);
    }
    else{
      push(atoi(s));
    }
  }
  printf("%d\n",pop());

  return 0;
}

void push(int a){
  S[++top] = a;
}
int pop(){
  top--;
  return S[top+1];
}