rt。

let g:x = 1
let g:y = 0

func! CursorMove()
    let g:y = g:y+1
    if g:y >= len(getline(g:x))
        let g:x = g:x+1
        let g:y = 0
    endif
endfunc

func IsNum(ch)
    if a:ch == '0'
        return 0
    elseif a:ch == '1'
        return 1
    elseif a:ch == '2'
        return 2
    elseif a:ch == '3'
        return 3
    elseif a:ch == '4'
        return 4
    elseif a:ch == '5'
        return 5
    elseif a:ch == '6'
        return 6
    elseif a:ch == '7'
        return 7
    elseif a:ch == '8'
        return 8
    elseif a:ch == '9'
        return 9
    endif
    return -1
endfunc

func! InputNum()
    let f = 1
    let X = 0
    while IsNum(getline(g:x)[g:y]) == -1
        if getline(g:x)[g:y] == '-'
            let f = -1
        endif
        call CursorMove()
    endwhile
    while IsNum(getline(g:x)[g:y]) != -1
        let X = X*10+IsNum(getline(g:x)[g:y])
        call CursorMove()
    endwhile
    return f*X
endfunc

let a = 0
let b = 0

func Solution()
    let a = InputNum()
    let b = InputNum()
    exec "echo a+b"
endfunc