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 <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <utility>
#include <ctime>
#define INF 999999999
#define mod 1000000007

#define rep(i,n) for(int i=0;i<int(n);i++)
#define rrep(i,n) for(int i=(n);i>=0;i--)
#define REP(i,a,b) for(int i=(a);i<int(b);i++)
#define all(x) (x).begin(),x.end()
#define pb push_back
#define MOD(x) (x%(mod))
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef vector<int> vi;
typedef pair<int,int> pi;

int dx[4]={1,0,-1,0};
int dy[4]={0,1,0,-1};
bool debug=false;
/*---------------------------------------------------*/

int haiku[45];
int num[6]={5,7,5,7,7,0};

void solve(int n){
  int s=0,e=0,cnt=0,sum=haiku[0];
  int dast=0;
  
  rep(i,n-5){
    dast=cnt=0;
    s=e=i;
    sum=haiku[i];
    
    while(s!=n&&e!=n){
      if(debug)cout<<"s: "<<s<<"  e:"<<e<<"  cheack( "<<cnt<<" ): "<<num[cnt]<<"  dast: "<<dast<<"  cnt: "<<cnt<<endl;
      if(cnt==5)break;
      if(sum==num[cnt]){
	s=e=e+1;sum=haiku[s];cnt++;
      }else if(sum<num[cnt]){
	e++;sum+=haiku[e];
      }else if(sum>num[cnt]){
	break;
      }
    }
    if(debug)cout<<endl;
    if(debug)cout<<"s: "<<s<<"  e:"<<e<<"  cheack( "<<cnt<<" ): "<<num[cnt]<<"  dast: "<<dast<<"  cnt: "<<cnt<<endl;
    if(cnt==5){
      cout<<i+1<<endl;
      break;
    } 
  }
}


int main(){
  int n;
  string s;
  while(cin>>n){
    if(n==0)break;
    rep(i,n){cin>>s;haiku[i]=s.size();}
    solve(n);
  }
}

C++: #include <algorithm>
#include <cstring>
#include <iostream>
#include <vector>
#include <cmath>
#include <math.h>
#include <stdio.h>
#include <iomanip>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <string>
#include <functional>
#define rep(i,n) for (int i = 0; i < (n); ++i)

using namespace std;
const int MOD = 1000000007;


typedef long long int ll; 
typedef pair<int,int> Pii;
typedef pair<ll,ll> Pll;

void floatOutPutSetup(){
    cout << fixed;
    cout << setprecision(10);
}

bool isku(vector<string> w,int s){
    int cor[]={5,7,5,7,7};
    int st = s;
    vector<int> m;
    rep(i,5){
        int t = cor[i];
        int sum = 0;
        for(int o = st;;o++ ){
            sum+=w[o].size();
            if(sum == t){
                st = o+1;
                break;
            }
            else if(sum > t)return false;
        }
    }
    return true;
}

int main(){
    int n;
    cin >>n;
    while(n){
        vector<string> w(n,"");
        rep(i,n)cin >> w[i];
        rep(i,n){
            if(isku(w,i)){
                cout<<i+1<<endl;
                break;
            }
        }
        cin>>n;
    }
    return 0;
}

C++: #include <bits/stdc++.h>
using namespace std;
#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,n)   FOR(i,0,n)
#define pb emplace_back
typedef long long ll;
typedef pair<int,int> pint;

int a[41];
int x[]={5,7,5,7,7};
int main(){
    int n;
    string s;
    while(cin>>n,n){
        rep(i,n){
            cin>>s;
            a[i]=s.size();
        }
        int ans=-1;
        rep(i,n){
            int cur=0,sum=0;
            FOR(j,i,n){
                sum+=a[j];
                if(sum>=x[cur]){
                    if(sum==x[cur]){
                        ++cur;sum=0;
                        if(cur==5){
                            ans=i+1;
                            break;
                        }
                    }
                    else break;
                }
                if(ans!=-1) break;
            }
            if(ans!=-1){
                cout<<ans<<endl;
                break;
            }
        }
    }
    return 0;
}

C++: #include <cstdio>
#include <string>
#include <vector>

int solve_testcase() {
    size_t n;
    scanf("%zu", &n);
    if (n == 0)
        return 1;

    std::vector<std::string> w(n);
    for (size_t i=0; i<n; ++i) {
        char buf[16];
        scanf("%s", buf);
        w[i] = buf;
    }

    const size_t sph[]={5, 7, 5, 7, 7};
    for (size_t res=0; res<n; ++res) {
        size_t counter=0, index=0;
        for (size_t i=0; res+i<n; ++i) {
            if (counter + w[res+i].length() > sph[index])
                break;  // match failed

            counter += w[res+i].length();
            if (counter == sph[index]) {
                ++index;
                counter = 0;
            }

            if (index == 5)
                return !printf("%zu\n", res+1);
        }
    }

    // maybe not reached
    return 0;
}

int main() {
    while (!solve_testcase()) {}

    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;
    }

    return -1;
}

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;
}