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"
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int INF = 1e9;
const ll LINF = 1e18;
template<class S,class T> ostream& operator << (ostream& out,const pair<S,T>& o){ out << "(" << o.first << "," << o.second << ")"; return out; }
template<class T> ostream& operator << (ostream& out,const vector<T> V){ for(int i = 0; i < V.size(); i++){ out << V[i]; if(i!=V.size()-1) out << " ";} return out; }
template<class T> ostream& operator << (ostream& out,const vector<vector<T> > Mat){ for(int i = 0; i < Mat.size(); i++) { if(i != 0) out << endl; out << Mat[i];} return out; }
template<class S,class T> ostream& operator << (ostream& out,const map<S,T> mp){ out << "{ "; for(auto it = mp.begin(); it != mp.end(); it++){ out << it->first << ":" << it->second; if(mp.size()-1 != distance(mp.begin(),it)) out << ", "; } out << " }"; return out; }

/*
 <url:http://judge.u-aizu.ac.jp/onlinejudge/description.jsp?id=1601&lang=jp>
 問題文============================================================
 =================================================================
 解説=============================================================
 ================================================================
 */

int n;
int solve(){
    int res = 0;
    vector<string> w(n); for(auto& in:w) cin >> in;
    vector<int> tanka = {5,7,5,7,7};
    for(int i = 0; i < w.size();i++){
        int I = 0;
        for(int j = i; j < w.size();j++){
           // cout << tanka << endl;
            if(w[j].length() < tanka[I]){
                tanka[I] -= w[j].length();
            }else if(w[j].length() == tanka[I]){
                tanka[I] = 0;
                I++;
                if(I == 5){
                    return i + 1;
                }
            }else{
                tanka = vector<int>{5,7,5,7,7};
                break;
            }
        }
    }
    return res;
}
int main(void) {
    cin.tie(0); ios_base::sync_with_stdio(false);
    while(cin >> n,n){
        cout << solve() << endl;
    }
    return 0;
}

C++: #include <iostream>
using namespace std;

const int step[5] = {5, 7, 5, 7, 7};

int N;
string S[40];

int solve() {
    for (int i = 0; i < N; ++i) {
        bool ok = true;
        int idx = i;
        for (int t = 0; t < 5; ++t) {
            int acc = 0;
            while (acc < step[t]) acc += S[idx++].size();
            if (acc != step[t]) {
                ok = false;
                break;
            }
        }
        if (ok)
            return i+1;
    }

    assert(false);
}

int main(void) {
    while (true) {
        cin >> N;
        if (N == 0) break;
        for (int i = 0; i < N; ++i)
            cin >> S[i];

        cout << solve() << endl;
    }
    return 0;
}

C++: #include <iostream>
#include <fstream>
#include <cstdio>
#include <cmath>
#include <vector>
#include <cstring>
#include <string>
#include <set>
#include <map>
#include <stack>
#include <queue>
#include <algorithm>
using namespace std;
 
#define REP(i,n) for(int i=0; i<n; ++i)
#define FOR(i,a,b) for(int i=a; i<=b; ++i)
#define FORR(i,a,b) for (int i=a; i>=b; --i)
#define pi M_PI
 
typedef long long ll;
typedef vector<int> VI;
typedef vector<ll> VL;
typedef vector<VI> VVI;
typedef pair<int,int> P;
typedef pair<ll,ll> PL;

int main() {
    int n;
    int w[5] = {5, 7, 5, 7, 7};
    while (cin >> n && n){
        VI a(n);
        REP(i,n) {
            string s;
            cin >> s;
            a[i] = s.length();
        }
        REP(s,n){
            int x = 0, i = s, j = 0, f = 1;
            while (f){
                x += a[i];
                i++;
                if (x == w[j]){
                    x = 0;
                    j++;
                }
                if (x > w[j]) f = 0;
                if (j == 5) break;
            }
            if (f) cout << s+1 << endl;
        }
    }

    return 0;
}

C++: #include<bits/stdc++.h>
char s[50],a[9]={5,7,5,7,7,-1};
main(){for(int i,j,p,n,q;scanf("%d\n",&n),n;){for(i=0;i<n;s[i++]=strlen(gets(s+i)));
for(i=j=0;j<6;i++)for(p=i,j=q=0;q>=0;)for(q=a[j++];q>0;q-=s[p++]);
printf("%d\n",i);
}}

C++: #include<iostream>

using namespace std;

signed main(){

   while(1){
      int n;
      cin>> n;
      if(!n) break;

      int w[n];
      for(int i=0; i<n; i++){
         string s;
         cin>> s;
         w[i]=s.size();
      }
      int b[]={5, 7, 5, 7, 7};
      for(int i=0; i<n; i++){
         int a=0, p=0;
         for(int j=i; j<n; j++){
            a+=w[j];
            if(a>b[p]){
               goto turai;
            }else if(a==b[p]){
               p++;
               if(p==5) break;
               a=0;
            }
         }
         if(p==5){
            cout<< i+1<< endl;
            break;
         }
         turai:;
      }

   }

   return 0;
}