#include <bits/stdc++.h>
#define ll long long
#define Accepted     ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
using namespace std;
ll arr[100005];
ll tt(ll hh,ll mm)
{
    return hh*60+mm;
 
}
int main()
{
    Accepted
    char cc;
    bool tr=0;
    string s,ss;
    ll a,ta,b,tb,hh,mm,st,et,cnt=0;
    cin>>a>>ta>>b>>tb>>hh>>cc>>mm;
    st=tt(hh,mm);
    et=st+ta;
    for(int i=5*60;i<24*60-1;i+=b)
    {
        if(i>st-tb&&i<et)
            cnt++;
    }
    cout<<cnt;
    return 0;
}
 

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