Below is the input:
以下是输入:
X1 = c("aaa", "aaa", "aaa", "qqq", "qqq", "qqq")
X2 = c("bbb", "bbb", "bbb", "rrr", "rrr", "rrr")
X3 = c("ccc", "ccc", "ccc", "ttt", "ttt", "ttt")
X4 = c("usa", "can", "usa", "ger", "rus", "ger")
X5 = c(400, 888, 500, 300, 456, 500)
df <- data.frame(X1,X2,X3,X4,X5)
X1 = c("aaa", "a
