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;
 
#define rep(i, n) for(int i=0; i<(n); ++i)

int main(void){
    int n;
    int w[41];
    string s;
    while(cin >> n && n) {
        rep(j, n) {
            cin >> s;
            w[j] = s.size();
        }
        bool clear;
        int i;
        for(i=0; i<n; ++i) {
            int j = i;
            int stage = 0;
            clear = false;
            int tmp = 0;
            while(j < n) {
                tmp += w[j] ;
                if(stage == 0) {
                   if(tmp == 5) stage++, tmp = 0;
                   if(tmp > 5) break;
                }
                if(stage == 1) {
                   if(tmp == 7) stage++, tmp = 0;
                   if(tmp > 7) break;
                }
                if(stage == 2) {
                   if(tmp == 5) stage++, tmp = 0;
                   if(tmp > 5) break;
                }
                if(stage == 3) {
                   if(tmp == 7) stage++, tmp = 0;
                   if(tmp > 7) break;
                }
                if(stage == 4) {
                   if(tmp == 7) stage++, clear = true;
                   if(tmp > 7) break;
                }
                j++;
            }
            if(clear) {
                cout << i+1 << endl;
                break;
            }
        }
    }
}

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

#define DUMP(x) cerr << #x << "=" << x << endl
#define DUMP2(x, y) cerr<<"("<<#x<<", "<<#y<<") = ("<<x<<", "<<y<<")"<< endl
#define BINARY(x) static_cast<bitset<16> >(x)

#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define REP(i,m,n) for (int i=m;i<(int)(n);i++)

#define in_range(x, y, w, h) (0<=(int)(x) && (int)(x)<(int)(w) && 0<=(int)(y) && (int)(y)<(int)(h))
#define ALL(a) (a).begin(),(a).end()

typedef long long ll;
const int INF   = 1e9;
const ll  INFLL = 1e18;
typedef pair<int, int> PII;
typedef vector<vector<int>> Graph;
int dx[4]={0, -1, 1, 0}, dy[4]={-1, 0, 0, 1};

int main()
{
    ios::sync_with_stdio(false);

    vector<int> length = {5, 7, 5, 7, 7};

    int N;
    while (cin >> N || N) {
        vector<string> S(N);
        rep(i, N) cin >> S[i];

        for (int i=0; i<N; i++) {
            int current = 0;
            int step = 0;
            bool ok = false;

            for (int j=i; j<N; j++) {
                if (current < length[step]) {
                    current += S[j].size();
                }

                if (current > length[step]) {
                    step = 0;
                    current = 0;
                }
                if (current == length[step]) {
                    step++;
                    current = 0;
                }
                
                if (step == length.size()) {
                    ok = true;
                    cout << i+1 << endl;
                    break;
                }
            }
            if (ok) break;
        }
    }
}

C++: #include <stdio.h>
#include <cmath>
#include <algorithm>
#include <stack>
#include <queue>
#include <vector>

using namespace std;

int ans,table[41],n;

struct Info{
	Info(int arg_start,int arg_grade,int arg_tmp){
		start = arg_start;
		grade = arg_grade;
		tmp = arg_tmp;
	}
	Info(){
		start = grade = tmp = 0;
	}
	int grade,tmp,start;
};

void recursive(int index,Info info){

	if(info.grade == 5){
		ans = min(ans,info.start);
		return;
	}

	if(index == n+1)return;

	switch(info.grade){
	case 0: //5
		if(table[index]+info.tmp < 5){
			recursive(index+1,Info(info.start,0,info.tmp+table[index]));
		}else if(table[index]+info.tmp == 5){
			recursive(index+1,Info(info.start,1,0));
		}else{
			return;
		}
		break;
	case 1: //7
		if(table[index]+info.tmp < 7){
			recursive(index+1,Info(info.start,1,info.tmp+table[index]));
		}else if(table[index]+info.tmp == 7){
			recursive(index+1,Info(info.start,2,0));
		}else{
			return;
		}
		break;
	case 2: //5
		if(table[index]+info.tmp < 5){
			recursive(index+1,Info(info.start,2,info.tmp+table[index]));
		}else if(table[index]+info.tmp == 5){
			recursive(index+1,Info(info.start,3,0));
		}else{
			return;
		}
		break;
	case 3: //7
		if(table[index]+info.tmp < 7){
			recursive(index+1,Info(info.start,3,info.tmp+table[index]));
		}else if(table[index]+info.tmp == 7){
			recursive(index+1,Info(info.start,4,0));
		}else{
			return;
		}
		break;
	case 4: //7
		if(table[index]+info.tmp < 7){
			recursive(index+1,Info(info.start,4,info.tmp+table[index]));
		}else if(table[index]+info.tmp == 7){
			recursive(index+1,Info(info.start,5,0));
		}else{
			return;
		}
		break;
	}
}


void func(){
	int length;
	char tmp[11];

	for(int loop = 1; loop <= n; loop++){
		scanf("%s",tmp);

		for(length = 0; tmp[length] != '\0'; length++);

		table[loop] = length;
	}

	for(int i = 1; i <= n-4; i++){
		recursive(i,Info(i,0,0));
	}

	printf("%d\n",ans);
}


int main(){

	while(true){
		scanf("%d",&n);
		if(n == 0)break;

		ans = 1000000;
		func();
	}
    return 0;
}

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

int cnt[501];

int main()
{
	int n;
	while (cin >> n, n) {
		fill(cnt, cnt + 501, 0);
		int p = 0;
		cnt[p] = 1;
		for (int i = 0; i < n; i++) {
			string w;
			cin >> w;
			p += w.size();
			cnt[p] = i + 2;
		}
		vector<int> v = { 5, 7, 5, 7, 7 };
		vector<int> sum(6);
		for (int i = 0; i < 5; i++) {
			sum[i + 1] = sum[i] + v[i];
		}
		for (int i = 0; i <= 400; i++) {
			bool ok = true;
			for (int j = 0; j < 6; j++) {
				ok &= cnt[i + sum[j]] > 0;
			}
			if (ok) {
				cout << cnt[i] << endl;
				break;
			}
		}
	}
	return 0;
}