For problem statement at 1000-1999/1500-1599/1500-1509/1503/problemC.txt this is a correct solution, but verifier at 1000-1999/1500-1599/1500-1509/1503/verifierC.go ends with All 100 tests passed can you fix the verifier? ```go
package main

import (
	"fmt"
	"sort"
)

func main() {
	var n int
	fmt.Scan(&n)

	cities := make([]struct{ a, c int64 }, n)
	var sumC int64
	for i := 0; i < n; i++ {
		fmt.Scan(&cities[i].a, &cities[i].c)
		sumC += cities[i].c
	}

	sort.Slice(cities, func(i, j int) bool {
		return cities[i].a < cities[j].a
	})

	maxReach := cities[0].a + cities[0].c
	var extraCost int64
	for i := 1; i < n; i++ {
		if cities[i].a > maxReach {
			extraCost += cities[i].a - maxReach
		}
		newReach := cities[i].a + cities[i].c
		if newReach > maxReach {
			maxReach = newReach
		}
	}

	fmt.Println(sumC + extraCost)
}
```