已AC，放心食用

#include<bits/stdc++.h>
using namespace std;
int fun(string s){
    int h = (s[0]-'0')*10+(s[1]-'0');
    int m = (s[3]-'0')*10+(s[4]-'0');
    return h * 60 + m;
}
int main(){
    int n;
    string s1,s2;
    cin>>n>>s1>>s2;
    int x = fun(s2)-fun(s1);
    if(n%x==0) cout<<n/x<<endl;
    else cout<<n/x+1<<endl;
}

#include<iostream>
using namespace std;
int m,st1,sp1,st2,sp2,n;
char x;
int main(){
    cin>>m;
    cin>>st1>>x>>st2;
    cin>>sp1>>x>>sp2;
    int st=st1*60+st2;
    int sp=sp1*60+sp2;
    if(m%(sp-st)==0)
        cout<<m/(sp-st);
    else
        cout<<m/(sp-st)+1;
    return 0;
}

已AC点赞再搬

#include<bits/stdc++.h>
using namespace std;
string s[10];
int sum[10],n,m,x,y,z,w;
char a,b,c,d;
int main()
{
    cin>>n>>s[1]>>s[2];
    for(int i=1;i<=2;i++)
    {
        a=s[i][0],b=s[i][1],c=s[i][3],d=s[i][4];
        x=a-48,y=b-48,z=c-48,w=d-48;
        sum[i]+=x*10*60+y*60+z*10+w;
    }
    if(n%(sum[2]-sum[1])==0)
    {
        m=n/(sum[2]-sum[1]);
    }
    else
    {
        m=n/(sum[2]-sum[1])+1;
    }
    cout<<m;
    return 0;
}