#include<iostream>
#include<algorithm>
#include<cstring>
#include<cstdio>
#include<bitset>
#include<cmath>
#include<ctime>
#include<queue>
#include<map>
#include<set>

#define int long long
#define fi first
#define se second
#define max Max
#define min Min
#define abs Abs
#define lc (x<<1)
#define rc (x<<1|1)
#define mid ((l+r)>>1)
#define pb(x) push_back(x)
#define lowbit(x) (x&(-x))
#define fan(x) (((x-1)^1)+1)
#define mp(x,y) make_pair(x,y)
#define clr(f,n) memset(f,0,sizeof(int)*(n))
#define cpy(f,g,n) memcpy(f,g,sizeof(int)*(n))
#define INF 0x3f3f3f3f

using namespace std;

inline int read()
{
	int ans=0,f=1;
	char c=getchar();
	while(c>'9'||c<'0'){if(c=='-')f=-1;c=getchar();}
	while(c>='0'&&c<='9'){ans=(ans<<1)+(ans<<3)+c-'0';c=getchar();}
	return ans*f;
}

inline void write(int x)
{
	if(x<0) putchar('-'),x=-x;
	if(x/10) write(x/10);
	putchar((char)(x%10)+'0');
}

template<typename T>inline T Abs(T a){return a>0?a:-a;};
template<typename T,typename TT>inline T Min(T a,TT b){return a<b?a:b;}
template<typename T,typename TT> inline T Max(T a,TT b){return a<b?b:a;}

const int N=2e5+5,mod=998244353;
int n,q;
char s[N];

struct Node
{
	int v1[2],v2[2];
	Node operator + (const Node &x)const
	{
		Node res;
		res.v1[0]=v1[0]+x.v1[0];
		res.v1[1]=v1[1]+x.v1[1];
		res.v2[0]=v2[0]+x.v2[0];
		res.v2[1]=v2[1]+x.v2[1];
		return res;
	}
}zr;

struct Seg
{
	Node val[N<<2];
	int tg[N<<2];
	void build(int x,int l,int r)
	{
		tg[x]=0;
		if(l==r)
		{
			val[x]=zr;
			val[x].v1[s[l]-'0']=1;
			val[x].v2[s[l]-'0']=l;
			return;
		}
		build(lc,l,mid);
		build(rc,mid+1,r);
		val[x]=val[lc]+val[rc];
	}
	void upd(int x)
	{
		tg[x]^=1;
		swap(val[x].v1[0],val[x].v1[1]);
		swap(val[x].v2[0],val[x].v2[1]);
	}
	void pushdown(int x)
	{
		if(tg[x])
		{
			upd(lc),upd(rc);
			tg[x]=0;
		}
	}
	void update(int x,int l,int r,int L,int R)
	{
		if(L<=l&&r<=R) return upd(x);
		pushdown(x);
		if(L<=mid) update(lc,l,mid,L,R);
		if(mid+1<=R) update(rc,mid+1,r,L,R);
		val[x]=val[lc]+val[rc];
	}
	Node query(int x,int l,int r,int L,int R)
	{
		if(L>R) return zr;
		if(L<=l&&r<=R) return val[x];
		pushdown(x);
		if(L<=mid&&mid+1<=R)
			return query(lc,l,mid,L,R)+query(rc,mid+1,r,L,R);
		else if(L<=mid) return query(lc,l,mid,L,R);
		else return query(rc,mid+1,r,L,R);
	}
}sum;

signed main()
{
	while(scanf("%lld%lld",&n,&q)!=EOF)
	{
		scanf("%s",s+1);
		sum.build(1,1,n);
		while(q--)
		{
			int l=read(),r=read();
			sum.update(1,1,n,l,r);
			Node t1=sum.query(1,1,n,1,n);
			Node t2=sum.query(1,1,n,1,t1.v1[1]);
			Node t3=sum.query(1,1,n,t1.v1[1]+1,n);
			int ans=(t3.v2[1]-t2.v2[0])*2+t1.v1[1];
			write(ans);puts("");
		}
	}
	return 0;
}