PROGRAMMING:Double layer beef Fort
$$Keven $$especially likes to eat double beef burger, and he decided to make his own double beef burger. We think that $$Keven $$can make a double beef burger from three pieces of bread, two pieces of beef cake and one piece of vegetable. Now $$Keven $$has only $$a $$piece of bread, $$B $$piece of beef cake, $$C $$piece of vegetables. How many double-layer beef castles can $$Keven $$make.
###Input format:
In one line, give three integers $$a, B, C $$, meaning as above$$（ 0<=a,b,c<=1,000,000,000)$$
###Output format:
Output a number in one line to indicate the maximum number of double beef castles that $$Keven $$can make.
###Input example:
Here is a set of inputs. For example:
```in
10 7 4
```
###Output example:
The corresponding output is given here. For example:
```out
three
```
answer：If there is no answer, please comment
###Input format:
In one line, give three integers $$a, B, C $$, meaning as above$$（ 0<=a,b,c<=1,000,000,000)$$
###Output format:
Output a number in one line to indicate the maximum number of double beef castles that $$Keven $$can make.
###Input example:
Here is a set of inputs. For example:
```in
10 7 4
```
###Output example:
The corresponding output is given here. For example:
```out
three
```
answer：If there is no answer, please comment