#include <stdio.h>
int top = 0;
int s = 0;
int n = 0, k = 1, c = 0, y = 0, x = 0;
char stl[10000] = {0};
long long exa[10000] = {0};
int main()
{
gets(stl);
x = 0;
while (stl[x] != 0)
{
if (stl[x] >= '0' && stl[x] <= '9')
{
y = 0;
while (stl[x] >= '0' && stl[x] <= '9')
{
y = y * 10 + (stl[x] - '0');
x = x + 1;
}
if (top < 10000)
{
exa[top] = y;
top = top + 1;
}
}
else if (stl[x] == '+')
{
if (top >= 2)
{
long long b = exa[top - 1];
long long a = exa[top - 2];
top = top - 2;
exa[top] = a + b;
top = top + 1;
}
x = x + 1;
}
else if (stl[x] == '-')
{
if (top >= 2)
{
long long b = exa[top - 1];
long long a = exa[top - 2];
top = top - 2;
exa[top] = a - b;
top = top + 1;
}
x = x + 1;
}
else if (stl[x] == '*')
{
if (top >= 2)
{
long long b = exa[top - 1];
long long a = exa[top - 2];
top = top - 2;
exa[top] = a * b;
top = top + 1;
}
x = x + 1;
}
else
{
x = x + 1;
}
}
if (top > 0)
{
printf("%lld", exa[top - 1]);
}
else
{
printf("0");
}
return 0;
}