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

void push(int);
int pop(void);


int S[4];
int top = 0;

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

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

      a = pop();
      b = pop();
      x = b-a;
      push(x);
    } else if ( s[0] == '*' ){
      x = pop()*pop();
        push(x);
    } else {
      x = atoi(s);
      push(x);

    }
  }

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

  return 0;
}

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

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


