#include <stdio.h>

void push(int);
int pop();

int top,S[1000];

int main(){
  int a,b;
  int 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;
}


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

