https://twitter.com/koher/status/1394985024013864964

main.swift

let pp = readLine()!.split(separator: " ")
let e = pp[0]
let y = Int(pp[1])!
let m = Int(pp[2])!
let d = Int(pp[3])!

let dd = [31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31]

struct YMD: Comparable {
    let y: Int
    let m: Int
    let d: Int
    init(_ y: Int, _ m: Int, _ d: Int) {
        self.y = y
        self.m = m
        self.d = d
    }
    static func <(lhs: YMD, rhs: YMD) -> Bool {
        if lhs.y < rhs.y {
            return true
        } else if lhs.y > rhs.y {
            return false
        } else {
            if lhs.m < rhs.m {
                return true
            } else if lhs.m > rhs.m {
                return false
            } else {
                return lhs.d < rhs.d
            }
        }
    }
}

let mRange = ...YMD(1912, 7, 29)
let tRange = YMD(1912, 7, 30)...YMD(1926, 12, 25)
let sRange = YMD(1926, 12, 25)...YMD(1989, 1, 7)
let hRange = YMD(1989, 1, 8)...YMD(2019, 4, 30)
let rRange = YMD(2019, 5, 1)...

func solve() -> YMD? {
    let ymd: YMD
    switch e {
    case "M":
        ymd = YMD(y + 1867, m, d)
        guard mRange.contains(ymd) else { return nil }
    case "T":
        ymd = YMD(y + 1911, m, d)
        guard tRange.contains(ymd) else { return nil }
    case "S":
        ymd = YMD(y + 1925, m, d)
        guard sRange.contains(ymd) else { return nil }
    case "H":
        ymd = YMD(y + 1988, m, d)
        guard hRange.contains(ymd) else { return nil }
    case "R":
        ymd = YMD(y + 2018, m, d)
        guard rRange.contains(ymd) else { return nil }
    default:
        preconditionFailure()
    }
    let isLeapYear = ymd.y.isMultiple(of: 4) && (!ymd.y.isMultiple(of: 100) || ymd.y.isMultiple(of: 400))
    if ymd.m == 2, isLeapYear {
        guard d <= 29 else { return nil }
    } else {
        guard d <= dd[ymd.m - 1] else { return nil }
    }
    
    return ymd
}

if let ymd = solve() {
    print(ymd.y, ymd.m, ymd.d)
} else {
    print(-1)
}