MY CODE:
#include <iostream.h>

#define maxN 5005
int i,Len,N;
int mn[maxN];
int L[maxN];
int R[maxN];
int pL[maxN];
int pR[maxN];

void search(int l,int r,int &il,int &ir,int &pl,int &pr){
    int j;
    il = ir = -1;
    for(j = 0;j < i;j++){
        if(r + 1 == L[j]){
            ir = j;
            pr = pL[j];
            break;
        }
    }
    for(j = 0;j < i;j++){
        if(l == R[j] + 1){
            il = j;
            pl = pR[j];
            break;
        }
    }
    for(j = 0;j < i;j++){
        if(r == R[j]){
            ir = j;
            pr = pR[j];
            break;
        }
    }
    for(j = 0;j < i;j++){
        if(l == L[j]){
            il = j;
            pl = pL[j];
            break;
        }
    }
}

int findroot(int k){
    if(mn[k] == -1)return -1;
    if(mn[k] == k)return k;
    int l = findroot(mn[k]);
    mn[k] = l;
    return l;
}

int add(int a,int b,int c){
    int pl,pr,il,ir;
    L[i] = a;
    R[i] = b;
    search(a,b,il,ir,pl,pr);
    if(il == -1 && ir == -1){
        pL[i] = 0;
        pR[i] = c;
        mn[i] = i;
    }
    if(il != -1 && ir == -1){
        int rl = findroot(il);
        mn[i] = rl;
        pL[i] = pl;
        pR[i] = (pL[i] + c) % 2;
    }
    if(il == -1 && ir != -1){
        int rr = findroot(ir);
        mn[i] = rr;
        pR[i] = pr;
        pL[i] = (pR[i] - c + 2) % 2;
    }
    if(il != -1 && ir != -1){
        int rl = findroot(il);
        int rr = findroot(ir);
        mn[i] = rl;
        if(rl == rr){
            if(((pl + c) % 2) != (pr % 2)){
                return 0;
            }
        }else{
            pL[i] = pl;
            pR[i] = (pL[i] + c) % 2;
            if(pr != pR[i])
                for(int k = 0;k < i;k++)
                    if(findroot(k) == rr)pR[k] =
(pR[k] + 1) % 2,pL[k] = (pL[k] + 1) % 2;
            int o = findroot(ir);
            mn[o] = i;
        }
    }
    return 1;
}

void main(void){
    for(;;){
        cin >> Len;
        if(Len == -1)break;
        cin >> N;
        int bad = 0;
        for(i = 0;i < N;i++){
            mn[i] = -1;
            int a,b;char k[10];
            cin >> a >> b >> k;
// FOR debug reasons only...
//            if(a == -1){cout << "Wrong input";return;}
//            if(b == -1){cout << "Wrong input";return;}
            if(!add(a,b,(k[0] == 'e') ? 0 : 1)){
                cout << i << "\n";
                bad = 1;
                for(i++;i < N;i++)
                    cin >> a >> b >>  k;
                break;
            }
        }
        if(!bad)cout << N << "\n";
    }
}

i know that this task from CEOI 99 but i don't want to see sol. and
theier test, because in that case it is a cheat :-)

But you can find your mistake!

And if I send you this test, is it cheat? :-)

> i know that this task from CEOI 99 but i don't want to see sol. and
> theier test, because in that case it is a cheat :-)