require "io2"

local function subleq(program)
    local words = program:split(" "):map(|w| -> tonumber(w))
    local sb = ""
    local ip = 0
    while true do
        local a = words[ip + 1]
        local b = words[ip + 2]
        local c = words[ip + 3]
        ip += 3
        if a < 0 then
            words[b + 1] = tonumber(io.readStr("Enter a character : ", 1, 1))
        elseif b < 0 then
            sb ..= string.char(words[a + 1])
        else
            words[b + 1] -= words[a + 1]
            if words[b + 1] <= 0 then ip = c end
            if ip < 0 then break end
        end
    end
    io.write(sb)
end

local program = "15 17 -1 17 -1 -1 16 1 -1 16 3 -1 15 15 0 0 -1 72 101 108 108 111 44 32 119 111 114 108 100 33 10 0"
subleq(program)