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#include <stdio.h>

#include <stdlib.h>

#include <string.h>

// 逆波兰表示法

int top, S[1000];

void push(int x) {

// top 加1 之后将元素插入 top 所指向的位置

S[++top] = x;

}

int pop() {

top--;

// 返回top所指的元素

return S[top + 1];

}

// input: 1 2 + 3 4 - * output: -3

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] == '-') {

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;

}