Go: package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
	"strings"
)

func main() {
	io := NewIo()
	defer io.Flush()
	for {
		n := io.NextInt()
		if n == 0 {
			break
		}
		s := make([]string, n)
		for i := 0; i < n; i++ {
			s[i] = io.NextLine()
		}
		w := [5]int{5, 7, 5, 7, 7}
		ans := 0
	OUTER:
		for i := 0; i < n; i++ {
			cnt, wc := 0, 0
			for j := i; j < n; j++ {
				wc += len(s[j])
				if wc == w[cnt] {
					cnt++
					wc = 0
					if cnt == 5 {
						ans = i + 1
						break OUTER
					}
				} else if wc > w[cnt] {
					break
				}
			}
		}
		io.Println(ans)
	}
}

// I/O template
type Io struct {
	reader    *bufio.Reader
	writer    *bufio.Writer
	tokens    []string
	nextToken int
}

func NewIo() *Io {
	return &Io{
		reader: bufio.NewReader(os.Stdin),
		writer: bufio.NewWriter(os.Stdout),
	}
}

func (io *Io) Flush() {
	err := io.writer.Flush()
	if err != nil {
		panic(err)
	}
}

func (io *Io) NextLine() string {
	var buff []byte
	for {
		line, isPrefix, err := io.reader.ReadLine()
		if err != nil {
			panic(err)
		}
		buff = append(buff, line...)
		if !isPrefix {
			break
		}
	}
	return string(buff)
}

func (io *Io) Next() string {
	for io.nextToken >= len(io.tokens) {
		line := io.NextLine()
		io.tokens = strings.Fields(line)
		io.nextToken = 0
	}
	s := io.tokens[io.nextToken]
	io.nextToken++
	return s
}

func (io *Io) NextInt() int {
	i, err := strconv.Atoi(io.Next())
	if err != nil {
		panic(err)
	}
	return i
}

func (io *Io) NextFloat() float64 {
	i, err := strconv.ParseFloat(io.Next(), 64)
	if err != nil {
		panic(err)
	}
	return i
}

func (io *Io) Println(a ...interface{}) {
	fmt.Fprintln(io.writer, a...)
}

func (io *Io) Printf(format string, a ...interface{}) {
	fmt.Fprintf(io.writer, format, a...)
}

func (io *Io) PrintIntSlice(a []int) {
	b := make([]interface{}, 0, len(a))
	for _, x := range a {
		b = append(b, x)
	}
	io.Println(b...)
}

func (io *Io) PrintStringSlice(a []string) {
	b := make([]interface{}, 0, len(a))
	for _, x := range a {
		b = append(b, x)
	}
	io.Println(b...)
}

func Log(name string, value interface{}) {
	fmt.Fprintf(os.Stderr, "%s=%+v\n", name, value)
}

func ExampleIo() {
	io := NewIo()
	defer io.Flush()
	a := make([]int, 0, 3)
	a[0], a[1], a[2] = io.NextInt(), io.NextInt(), io.NextInt()
	io.Println(a)
	io.PrintIntSlice(a)
	Log("io", a)
}

C++: #include <bits/stdc++.h>
#define ll long long
#define INF 1000000005
#define MOD 1000000007
#define EPS 1e-10
#define rep(i,n) for(int i=0;i<(int)(n);++i)
#define rrep(i,n) for(int i=(int)(n)-1;i>=0;--i)
#define srep(i,s,t) for(int i=(int)(s);i<(int)(t);++i)
#define each(a,b) for(auto (a): (b))
#define all(v) (v).begin(),(v).end()
#define len(v) (int)(v).size()
#define zip(v) sort(all(v)),v.erase(unique(all(v)),v.end())
#define cmx(x,y) x=max(x,y)
#define cmn(x,y) x=min(x,y)
#define fi first
#define se second
#define pb push_back
#define show(x) cout<<#x<<" = "<<(x)<<endl
#define spair(p) cout<<#p<<": "<<p.fi<<" "<<p.se<<endl
#define svec(v) cout<<#v<<":";rep(kbrni,v.size())cout<<" "<<v[kbrni];cout<<endl
#define sset(s) cout<<#s<<":";each(kbrni,s)cout<<" "<<kbrni;cout<<endl
#define smap(m) cout<<#m<<":";each(kbrni,m)cout<<" {"<<kbrni.first<<":"<<kbrni.second<<"}";cout<<endl

using namespace std;

typedef pair<int,int> P;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<double> vd;
typedef vector<P> vp;

const int MAX_N = 100005;

int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    while(1){
        int n;
        cin >> n;
        if(n == 0){
            break;
        }
        vector<int> vec(n);
        rep(i,n){
            string s;
            cin >> s;
            vec[i] = len(s);
        }
        rep(i,n){
            int flag = 0;
            int nw = 0;
            bool fl = true;
            srep(j,i,n){
                if(flag == 0){
                    nw += vec[j];
                    if(nw == 5){
                        flag = 1;
                        nw = 0;
                    }else if(nw > 5){
                        fl = false;
                        break;
                    }
                }else if(flag == 1){
                    nw += vec[j];
                    if(nw == 7){
                        flag = 2;
                        nw = 0;
                    }else if(nw > 7){
                        fl = false;
                        break;
                    }
                }else if(flag == 2){
                    nw += vec[j];
                    if(nw == 5){
                        flag = 3;
                        nw = 0;
                    }else if(nw > 5){
                        fl = false;
                        break;
                    }
                }else if(flag == 3){
                    nw += vec[j];
                    if(nw == 7){
                        flag = 4;
                        nw = 0;
                    }else if(nw > 7){
                        fl = false;
                        break;
                    }
                }else{
                    nw += vec[j];
                    if(nw == 7){
                        break;
                    }else if(nw > 7){
                        fl = false;
                        break;
                    }
                }
            }
            if(fl){
                cout << i+1 << "\n";
                break;
            }
        }
    }
    return 0;
}

C++: #include<iostream>
#include<vector>
#include<string>
using namespace std;
#define DBG cout<<"!"<<endl;
vector<int> size;
int fin;
void dfs(int flag,int count,int i,int now){
  switch(flag){
  case 0:case 2:
    if(count+size[i]>5)
      return;
    if(count+size[i]==5){
      if(flag==0){	
	flag=1;
      }
      if(flag==2)
	flag=3;
    }
    if(flag==0||flag==2)
      dfs(flag,count+size[i],i+1,now);
    else
      dfs(flag,0,i+1,now);
    break;
  case 1:case 3:
    if(count+size[i]>7)
      return;
    if(count+size[i]==7){
      if(flag==1)
	flag=2;
      if(flag==3)
	flag=4;
    }
    if(flag==1||flag==3)
      dfs(flag,count+size[i],i+1,now);
    else
      dfs(flag,0,i+1,now);
    break;
  case 4:
    if(count+size[i]>7)
      return;
    if(count+size[i]==7){
      fin=1;
      cout<<now<<endl;
      return;
    }
    dfs(flag,count+size[i],i+1,now);
  }
}
int main(){
  int n;
  while(cin>>n,n!=0){
    string str2;
    for(int i=0;i<n;i++){
      cin>>str2;
      size.push_back(str2.size());
    }
    for(int i=0;i<n;i++){
      int flag;
      int cnt=size[i];
      int now=i+1;
      if(fin==1)
	break;
      if(cnt==5)
	flag=1;
      else
	flag=0;
      if(cnt>5)
	continue;
      dfs(flag,cnt,i+1,now);
    }
    size.clear();
  }
  return 0;
}

C++: #include<bits/stdc++.h>
#define Pasharin using namespace std

Pasharin;
int main(){
  int n;
  int a[]={5,7,5,7,7};
  while(cin>>n,n){
    string s[n];
    int x=0,y=0;
    for(int i=0;i<n;++i) cin>>s[i];
    int j=0;
    bool flag=false;
    for(j=0;j<n;++j){
      for(int i=j;i<n;++i){
        x+=(int)s[i].size();
        if(x==a[y]){
          x=0;
          y++;
          if(y==5){
            cout<<j+1<<endl;
            flag=true;
            break;
          }
        }
        else if(x>a[y]){
          x=0,y=0;
          break;
        }
      }
      if(flag) break;
    }
  }
  return 0;
}