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

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

int top, S[1000];

int main()
{
  int n, m;
  char s[100];
  top=0;

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

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

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