// c
# 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 a,b,x;
    char s[100];
    top = 0 ;
    // 読み込みの指定がない場合はEOF判定をする
    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;
}
