if let n = readLine(), let N = Int(n) {
    if let line1 = readLine(), let rgb = line1.split(separator: " ").compactMap({Int($0)}) as? [Int], rgb.count==3 {
        var dpR = rgb[0], dpG = rgb[1], dpB = rgb[2]
        var prevR = dpR, prevG = dpG, prevB = dpB

        for _ in 1..<N {
            if let lineN = readLine(), let RGB = lineN.split(separator: " ").compactMap({Int($0)}) as? [Int], RGB.count==3 {
                dpR = RGB[0] + min(prevG, prevB)
                dpG = RGB[1] + min(prevR, prevB)
                dpB = RGB[2] + min(prevR, prevG)
                prevR = dpR; prevG = dpG; prevB = dpB
            }
        }

        print(min(dpR, dpG, dpB))
    }
}