#include<stdio.h>
#include<stdlib.h>
#include<string.h>

int top,S[1000];

void push(int x){

  top++;
  S[top] = x;
}

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



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

  while( scanf("%s",s) != EOF ){
    if ( s[0] == '+' ){
      a = pop();
      b = pop();
      push(a + b);
    }
    else if ( s[0] == '-' ){
      a = pop();
      b = pop();
      push(b - a);
    }
    else if ( s[0] == '*' ){
      a = pop();
      b = pop();
      push(a * b);
    }
    else {
      x = atoi(s);
      push(x);
    }
  }

  printf("%d\n",pop());

  return 0;
}
