#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define N 1000
int top,S[N];

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

int main(){
  int a,b;
  top=0;
  char s[100];
  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;
}

