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++: #define  _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <algorithm>
#include <utility>
#include <functional>
#include <cstring>
#include <queue>
#include <stack>
#include <math.h>
#include <iterator>
#include <vector>
#include <string>
#include <set>
#include <math.h>
#include <iostream> 
#include <random>
#include<map>
#include <iomanip>
#include <time.h>
#include <stdlib.h>
#include <list>
#include <typeinfo>
#include <list>
#include <set>
#include <cassert>
#include<fstream>
#include <unordered_map>  
using namespace std;
#define Ma_PI 3.141592653589793
#define eps 0.00000000000000000000000001
#define LONG_INF 10000000000000000
#define GOLD 1.61803398874989484820458
#define MAX_MOD 1000000007
#define REP(i,n) for(long long i = 0;i < n;++i)
int main() {
#define int long long 
	while (true) {
		int n;
		cin >> n;
		if (n == 0) return 0;
		vector<int> cnt;
		REP(i, n) {
			string s;
			cin >> s;
			cnt.push_back(s.length());
		}
		for (int i = 0; i < cnt.size(); ++i) {
			int tmp_a = cnt[i];
			for (int q = i + 1;; ++q) {
				if (tmp_a == 5) {
					int tmp_b = cnt[q];
					for (int j = q + 1; ; ++j) {
						if (tmp_b == 7) {
							int tmp_c = cnt[j];
							for (int t = j + 1;;++t){
								if (tmp_c == 5) {
									int tmp_d = cnt[t];
									for (int p = t + 1;; ++p) {
										if (tmp_d == 7) {
											int tmp_e = cnt[p];
											for (int tea = p + 1;; ++tea) {
												if (tmp_e == 7) {
													cout << i+1 << endl;
													goto ok;
												}
												if (tea == cnt.size()) break;
												tmp_e += cnt[tea];
												if (tmp_e > 7) break;
											}
										}
										if (p == cnt.size()) break;
										tmp_d += cnt[p];
										if (tmp_d > 7) break;
									}
								}
								if (t == cnt.size()) break;
								tmp_c += cnt[t];
								if (tmp_c > 5) break;
							}
						}
						if (j == cnt.size()) break;
						tmp_b += cnt[j];
						if (tmp_b > 7) break;
					}
				}
				if (q == cnt.size()) break;
				tmp_a += cnt[q];
				if (tmp_a > 5) break;
			}
		}
	ok:;
	}
}

C++: #include <stdio.h>
#include <algorithm>
#include <iostream>
#include <vector>
#include <string>
using namespace std;
int make(int w,int p);

vector<string> a(40);

int main() {
  int n;
  scanf ("%d",&n);
  while(n){

    for(int t=0;t<n;t++){
      //scanf ("%s",a[t]);
      cin >> a[t];
    }
    for(int t=n;t<40;t++){
      //scanf ("%s",a[t]);
      a[t]="";
    }
    int end=0;
    int k=0;
    for(k=0;k<n;k++){
      int q=k;
      if(make(q,5)>=1){
        q=1+make(q,5);
        if(make(q,7)>=1){
          q=1+make(q,7);
          if(make(q,5)>=1){
            q=1+make(q,5);
            if(make(q,7)>=1){
              q=1+make(q,7);
              if(make(q,7)>=1){
                end=1;
                //printf("qwqw\n");
              }
            }
          }
        }
      }
      if(end==1) break;
    }
    printf("%d\n",k+1);
    scanf ("%d",&n);
  }
}


int make(int w,int p){
  int l=a[w].size();
  int r=0;
  if(l==p){
    return w;
  }
  else{
    if(l<p){
      r=make(w+1,p-l);
      //printf("%d\n",r);
      return r;
    }
    else{
      return -1;
    }
  }
}

C++: #include<deque>
#include<queue>
#include<vector>
#include<algorithm>
#include<iostream>
#include<set>
#include<cmath>
#include<tuple>
#include<string>
#include<chrono>
#include<functional>
#include<iterator>
#include<random>
#include<unordered_set>
#include<array>
#include<map>
#include<iomanip>
#include<assert.h>
#include<bitset>
#include<stack>
#include<memory>
using namespace std;
using namespace std::chrono;
typedef long long int llint;
typedef double lldo;
#define mp make_pair
#define mt make_tuple
#define pub push_back
#define puf push_front
#define pob pop_back
#define pof pop_front
#define fir first
#define sec second
#define res resize
#define ins insert
#define era erase
/*cout<<fixed<<setprecision(20);cin.tie(0);ios::sync_with_stdio(false);*/
const llint mod=998244353;
const llint big=2.19e17+1;
const long double pai=3.141592653589793238462643383279502884197;
const long double eps=1e-15;
template <class T,class U>bool mineq(T& a,U b){if(a>b){a=b;return true;}return false;}
template <class T,class U>bool maxeq(T& a,U b){if(a<b){a=b;return true;}return false;}
llint gcd(llint a,llint b){if(a%b==0){return b;}else return gcd(b,a%b);}
llint lcm(llint a,llint b){if(a==0){return b;}return a/gcd(a,b)*b;}
template<class T> void SO(T& ve){sort(ve.begin(),ve.end());}
template<class T> void REV(T& ve){reverse(ve.begin(),ve.end());}
template<class T>llint LBI(vector<T>&ar,T in){return lower_bound(ar.begin(),ar.end(),in)-ar.begin();}
template<class T>llint UBI(vector<T>&ar,T in){return upper_bound(ar.begin(),ar.end(),in)-ar.begin();}
bool solve(void){
	int n,i,j;cin>>n;
	if(n==0){return false;}
	vector<int>ta(n+1);
	for(i=0;i<n;i++){string s;cin>>s;ta[i]=s.size();}
	ta[n]=9999999;
	int tanka[5]={5,7,5,7,7};
	for(i=0;i<n;i++){
		int bas=0,num=0;
		for(j=i;;j++){
			num+=ta[j];
			if(num>tanka[bas]){break;}
			if(num==tanka[bas]){bas++;num=0;}
			if(bas==5){cout<<i+1<<endl;return true;}
		}
	}
	
	return true;
}
int main(void){
	while(solve()){}
}