题解 | 小红的优惠券

package main

import (
	"bufio"
	"fmt"
	"os"
)

func main() {
buf := bufio.NewReader(os.Stdin)
var n,m int
fmt.Fscan(buf, &n,&m)
type sale struct{
    price,save int
}
var a,b int
max := 0
for i:=0;i<m;i++{
    fmt.Fscan(buf,&a,&b)
    if a<=n && b>=max{
        max = b
    }
}
fmt.Print(n-max)
}