#include<stdio.h>

//??????????????????????????????????????????
int top,S[1000];

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

  printf("%d\n",pop());
  
  return 0;
}