Cyl

思路：

一道简单的思维题，自己推吧。。。

#include <iostream>
#include <cstdio>
#include <algorithm>
#include <cmath>
using namespace std;

int n, m;
int stepn, stepm;
int ans;

int main(){
    freopen ("cyl.in", "r", stdin);
    freopen ("cyl.out", "w", stdout);
    scanf("%d%d", &n, &m);
    if( (n - 1) % 3 == 0 ){
        stepn = (n - 1) / 3 * 2;
        stepm = (m - 1) % 3 + (m - 1) / 3 * 2;
        ans = stepn + stepm;
    }
    else if(n < 4){
        if( (m - 1) % 3 == 0 ){
            stepn = n - 1;
            stepm = (m - 1) / 3 * 2;
            ans = stepn + stepm;
        }
        else if(n == 3 && m == 3) ans = 8;
        else if(n == 3){
            if( (m - 1) % 3 == 0 ) ans = (m - 1) / 3 * 2 + 2;
            else ans = (m - 1) / 3 * 2 + (m - 1) % 3 + 4;
        }
        else ans = -1;
    }
    else{
        stepn = (n - 1) % 3 + (n - 1) / 3 * 2;
        stepm = (m - 1) % 3 + (m - 1) / 3 * 2;
        ans = stepn + stepm;
    }
    printf("%d", ans);
    return 0;
}