#include <stdio.h>
#include <string.h>
int a=0,b=0;
char s[201],stack1[201];
int stack2[201];
void push1(char k)
{
stack1[a]=k;
a++;
}
void push2(char v)
{
stack2[b]=v;
b++;
}
char pop1()
{
a--;
return stack1[a];
}
int pop2()
{
b--;
return stack2[b];
}
int main()
{
int ret1=0,ret2=0;
gets(s);
for (int i=0; i<strlen(s); i++)
{
if (s[i]=='*'||s[i]=='+'||s[i]=='-')
{
push1(s[i]);
ret1=pop2();
ret2=pop2();
if (s[i]=='*')
{
push2((ret1*ret2));
}
else if (s[i]=='+')
{
push2((ret1+ret2));
}
else
{
push2((ret2-ret1));
}
}
else if (s[i]!=' ') push2(s[i]-'0');
if (i==strlen(s)-1) printf("%d",pop2());
}
return 0;
}